Query expresion not working using IIF(IsError

[ia2mn]

I am building an expresion to simply take the number from one field in the query and divide it by another number in the query. However some of the corresponding numbers in the 2nd field are 0 so I will get a #Error in return. I thought I'd beat this by using IIF(IsError but when I do, I still am getting an #Error return and its only the issues that would correspond to a Div/0 error. Here is the expression please tell me what you think.



Expr1: IIf(IsError([CurrentMonth]/[PreviousMonth]),"0",[CurrentMonth]/[PreviousMonth])

Thank You

[pbaldy]

I would test for PreviousMonth being 0.