This works, but as an alternative, if your value is in a particular cell
(say, J100), use
=IF(J100=0, 0, SUM(A1:J99)/J100)
This is more efficient than calculating your formula twice, and has the
added benefit of not masking other errors the way ISERROR() does.
> Place an IF statement to trap the error and return a zero, as such:
>
> =IF(ISERROR(yourformula),0,yourformula)
>
> Now, when your formula returns an error, zero will be the result
> displayed.