I'm unable to post the db, but I think the function is in a standard module. Access recognizes it as a function, and I did I direct copy/paste of the code.
'This code was originally written by Keri Hardwick.
'It is not to be altered or distributed,
'except as part of an application.
'You are free to use it in any application,
'provided the copyright notice is left unchanged.
'Code Courtesy of
Function Nnz(testvalue As Variant) As Variant
'Not Numeric return zero
If Not (IsNumeric(testvalue)) Then
Nnz = 0
Nnz = testvalue