In my spreadsheet I have the following formula:

=IF(ISBLANK(Z4),"",IFERROR((VLOOKUP(Z4,'New Assessments'!$B$2:$U$227,10,FALSE)),X4))

I keep adding and deleting rows to the New Assessments sheet.
When I delete lines, the part of the formula $U$227 decreases, but when I paste new lines, this number does not increase.
Therefore my vlookup is only checking part of the range I need to check.

How can I fix the formula so that the $U$999 stays the same no matter what I do to the New Assessments sheet?

Regards,

Julio