I posted this a few days ago and got some good responses, but nothing that's
actually accomplishing what I had hoped (maybe it really just can't be done)

The specifics a
Creating an NPO reimbursement form where, in order for the form to be valid,
the employee needs to enter a project code into a column entitled '"Project"

The goal is to make it so that if this column is not filled in, an error
message will show up in the Grand Total or the person will be unable to
complete any more cells--sort of an enforced entry

Excel details:
Project column is column J
Grand Total cell is L22
Columns where expenses are entered are from B to I (Project is last column)
Rows where expenses are entered are from 8 to 21, with 22 being each
column's total
Not all rows/cells have to be filled in for the form to be valid but if a
row is used, it must (ideally) have a required Project code

I have tried:
1. An IF statement in the Grand Total cell (L22) but this leaves me with a
'true' or 'false' entry, not a number as it needs to be
2. A Validation where the employee has to select from a list of project
codes but an erro will only show up if they type an incorrect code, not if
they leave it blank

I'm new to this, so any other thoughts, ideas or help at all will b greatly
appreciated. Thank you in advance!