Troubleshooting

Start with the editor's Problems tab and the One row view: it shows the formula with the row's actual values filled in, which explains most surprises.

Error messages

Message	Usual cause	Fix
Missing operator between {[A]} and {[B]}	Two fields next to each other, e.g. clicked one after the other in the Fields list	Put an operator or comma between them: {[A]} + {[B]}
Unexpected field, an operator or comma is probably missing before it	A value right before a field, e.g. 5 {[A]}	Add the missing operator: 5 * {[A]}
Unexpected token / missing ) after argument list	Unbalanced brackets or quotes	Use Format, or check that every (, [, { and ' is closed
... is not defined	A misspelt function or variable (sum instead of Sum, row.Hours outside a function)	Check the spelling. Names are case-sensitive
Cannot read properties of null (reading 'x')	A value is empty: a missing lookup, an empty date	Use ?. and ??: Rows.find(...)?.Rate ?? 0
Invalid DateTime / empty date result	DateTime.fromISO received an empty value or a non-ISO text	Guard it: {[Date]} ? DateTime.fromISO({[Date]}) : null
Cannot assign to read only property / sort fails	Sorting or changing reference data	Copy first: [...{[Tasks_MergedData_]}].sort(...)
Circular reference detected	Fields that use each other in a loop	Break the loop. The dialog won't save a field that refers to itself
Warning: field not found	A token for a field that was renamed or deleted, or a snippet placeholder like {[Value]}	Replace the token by clicking the right field

Wrong results without an error

Symptom	Cause	Fix
Result is 0 or empty although matching child rows exist	Key types differ: number 1 vs text "1"	Rows.filter(ref, 'ProjectNo', Number({[ProjectNo]})) or String(...)
Sum gives 0 / too little	Numbers stored as text are skipped	Sum({[Amount]}.map(Number))
Aggregated value differs between the editor and the dashboard	The editor uses the top 10 preview rows	Switch on Disable data preview limit in the designer, see Preview uses sample rows
KPI doesn't change when a dashboard filter is applied	Aggregated fields are calculated before dashboard filters, by design	Filter in the data source, or put the condition in the formula with SumIf
Conditional total looks random	SumIf given lists from different sources ({[Tasks_Hours]} with {[Status]})	Use lists from the same source: {[Tasks_Hours]} with {[Tasks_Status]}
Number shows as text, or doesn't sort numerically	Column type is Single Line of Text	Set the type to Number
Child dynamic column is missing in the reference rows	Its property name is internal (column_...), not the display name	Insert it from the expanded All rows (reference) list

Performance

If a data source with Reference only children loads slowly:

1. Replace .filter(...), .find(...) and SumIf over reference data with Rows.filter / Rows.find / Rows.sum (why).
2. Limit the child data source with a filter or a smaller row limit. It's always loaded in full.
3. Avoid sorting a copy of the whole reference list in every row. Rows.max / Rows.min are calculated once.

Still stuck?

Send the Sintel BI team the formula, the column type and a screenshot of the One row view of a failing row.