Excel2003 ... I have 10 WorkBooks ... WorkBook 10 is a Summary of WorkBooks 1-9

In WorkBook 10 I have an AVERAGE formula linking back to the other 9
WorkBooks.

So far Link & Formula are working fine in WorkBook 10 with excepiton of
#Div/0 error which is preventing a SUM(myrange) Formula from working.

I can't use =if(iserror(myformula),"",myformula) because my Formula is too
long.

So ... is there some simple way to SUM a Range & ignore the #Div/0 error?

Thanks ... Kha