Formula in Display section not working

[manueurofax]

I'm having trouble identifying in the Display section of a Form if the form is in edit mode...

I use the expression I found:
IN([_RowNumber], table-name[_RowNumber])

It keeps giving me the problem that it doesn't find [RowNumber], what can I do?

Unable to find column '_RowNumber'

[LeviP]

Try to use ISBLANK([_RowNumber]) or ISNOTBLANK([_RowNumber])

perhaps because of the use of IN in this field which is not an ENUM