Limits and troubleshooting

What TapeHawk refuses in an indicator script, the common error messages and what they mean, why a script can draw nothing, and what to do when your indicators stop running.

Reading a message

The indicator editor shows the server's own messages: what is wrong, the position (line 3, col 14), and often a hint about what to write instead. The code a message quotes between backticks is your own.

The checker stops at the first problem it finds, so fixing one can reveal the next.

Common errors

The message contains	What it means	What to do
`x` is not declared	A typo, a name used above the line that declares it, a plot name used as a value, or a list word outside a comparison with its own input	Check the spelling and the order. To use what a plot draws, name the value first and plot the name
there is no function `f`	There is no built-in function `f`	See Functions
`f` needs 2 parameters, got 1	`f` takes a different number of arguments	See the function's signature
`is outside the range 1..4000`	A window length is outside 1 to 4,000	Use a smaller length, or a smaller `max` on the input
`indented with a tab`	A line is indented with a tab	Indent with spaces
`this indent level does not match any open block`	A line's indentation does not line up with the `if` it belongs to	Indent the body of each `if` or `else` by the same amount
`comparisons cannot be chained`	A chained comparison, `a < b < c`	Write `a < b and b < c`
`x` is already declared at line	`x` is declared twice	Rename one of them
`x` is a built-in function or `is a built-in source`	`x` is the name of a built-in function or of a source — `t`, `day` and `vol` are sources too	Choose another name
`x` is a language keyword	A name you declared is one of `var` `if` `else` `and` `or` `not`	Choose another name
`x` is a keyword, not a value	A keyword where a value belongs — usually one side of `and`, `or` or a comparison is missing	Complete the expression
cannot infer the domain of `p`	The checker cannot tell what kind of number plot `p` holds	Add `, domain price`, `count`, `osc100` or `zero` — see `plot`
`the definition draws nothing, marks nothing, and alerts nothing`	The script has no `plot` or `mark`	Add a `plot`
`a string cannot be used in an expression`	Text in quotes inside an expression	Use a number, or move the text to a label
`unexpected character`	A character the language has no use for, such as `%`, `&`, `^` or `?`	See Operators
`cannot read … here`	A word or symbol in a place where it cannot go	Check the line against the syntax of what it declares
`x` does not exist yet to reassign	`:=` on a name that was not declared with `var` or inside the statements	Declare it with `var x = …` above
`is not a statement`	An `input`, `plot` or `alert` inside an `if` — the message names which	Move it out of the `if`, above the statements for an `input`
`input` must come above every statement	An `input` below the first `var`, `if` or `:=`	Move every `input` above the statements
`mark m` needs `@print`, `@book` or `@cell`	A `mark` on the bar clock	Marks need an event clock
`f` can only be read under `@print`	A trade-clock function in a script on another clock	Add `@print` at the top, or use a bar-clock function
`name is … characters long, limit is 40`	A name longer than 40 characters	Shorten it
`compiles, but a condition cannot carry an alert`	The script declares an `alert`, which TapeHawk no longer accepts. The hint says what the script can do instead: on the trade or footprint-column clock the line can become a `mark`; a candle script cannot announce anything, and an order-book signal cannot carry an alert yet	Delete the line — see `alert`
`bars of warm-up and the window tops out at 1000`	The script needs more than 1,000 bars of warm-up at the largest values its inputs may take	Lower the `max` of inputs used as lengths, or use shorter windows
`fuel per run` or `fuel per event`	A bar-clock script asks for more work over the candles it runs on than one script may do, or an event-clock script for more work on a single trade or order-book frame. A footprint-column script with a `mark` is checked over the two columns each of its checks runs	Shorten windows, draw fewer lines, or read a narrower range of the order book
`indicators, limit is`	Your account holds as many indicators as it may	Delete one you no longer use, then save again
`total indicator cost`	Saving would push the work of all your indicators together past what an account may use	Shorten windows or delete an old indicator. Saving a cheaper version of a script is always allowed

Limits

A script is refused, with a message, when it goes past any of these:

What	Limit
The script	65,536 bytes
Indicator or value name	40 characters
Window length	1 to 4,000
Warm-up of a bar-clock script	1,000 bars, at the largest values its inputs may take
Choices in a list input	20
Array slots, all arrays together	4,000
`mark` declarations in a script	8
A mark's `cap`	100 a minute
A mark's `title` or `msg`	512 bytes and 8 placeholders
Nesting of expressions and `if` bodies	64 deep

Some limits have no fixed number you can plan around, and are set by TapeHawk:

The work a script may do in one run: over the candles it is given on the bar clock, on one trade or order-book update, or over the footprint columns a check covers. Long windows, many lines and wide order-book ranges cost more.
The work all your indicators may do together, and how many indicators an account holds. Editing an existing indicator into a cheaper one is always allowed, even when the account is over.
The size of a script. A very long script is refused when it is checked or saved.

A script that draws nothing

Go through these in order:

Does it compile? When the editor lists an error, the preview keeps showing the last version that compiled, and a script with an error cannot be saved.
Is it on the right panel? A script with @print or @book at the top draws on heatmap panels only — a candles or footprint panel's menu lists it with a note instead. A @book line starts empty and fills in as the book updates, and a @cell script marks only columns that have closed, so the newest bar has none yet — see Your indicator on a chart.
Is the warm-up longer than the history? A line is blank until its windows have filled, at the settings in use — a 200-bar average over the last 150 bars on screen draws nothing. Scroll back to load more bars, or shorten the window. The warm-up the editor reports is counted at the inputs' defaults, so a higher setting on a panel needs more bars.
Are there too many bars on screen? A script can read only so many bars at once — fewer the more lines, windows, sources and array slots it has. Past that its row in the info bar shows a ⚠ asking you to scroll forward or zoom in.
Does it read order flow? delta, cvd and vol need order flow on the panel.
- A saved indicator that reads any of them loads order flow on the panel it is added to, whatever the domains of its lines.
- The editor's preview loads order flow for the draft too.
- Order flow exists only on the timeframes and candle shapes where order-flow indicators draw — see Where an indicator can be drawn — and on a live-only symbol it reaches back only about half an hour — see Recorded symbols and live-only symbols.
Is every value nan? A comparison with nan is false, and a value built on its own prev that starts from nan stays nan — select(close > prev(top), close, prev(top)) never gets going, while max(close, prev(top)) does. Plot the intermediate values one at a time to find where the numbers disappear.
Did the script stop? An array index outside the array, or decay given nan, stops the script as it runs and nothing is drawn. Guard the index or the value with if.

A saved indicator whose script no longer compiles — after a change in the language — is listed in the indicator menu with a note to open the editor and fix it.

When your indicators are not running

A banner at the top of the editor says when TapeHawk is not running the alerts on the indicators you wrote:

Alerts on user-written indicators are temporarily switched OFF by an operator, so they do not notify. Your scripts are stored untouched.
Under heavy load, a banner says how many alerts on your indicators are temporarily not being evaluated — one for each rule on each market and timeframe it watches. It clears by itself when the load drops.

Your scripts are not changed in either case, but while a banner shows, those rules are not evaluated and send no notifications — see Custom indicators.