If i put the following info into my worksheet it comes up
with a circular reference error.

Public Function PromptPayment()
MsgBox "Please issue Prompt Payment Letter"
End Function

then in cell G4 i input the following:-
=DAYS360(E4,F4)=IF(G415,PromptPayment(),"")

and if i just input this instead
=IF(G415,PromptPayment(),"")

I still get the same error.
any suggestions welcome.
i am not an expert in this field.

thanks