=IIf(

IsNothing(Sum(Fields!divisor.Value)) Or Sum(Fields!divisor.Value) = 0.0,

"",

Sum(Fields!value.Value) / IIf(IsNothing(Sum(Fields!divisor.Value)) Or Sum(Fields!divisor.Value) = 0.0, 1, Sum(Fields!divisor.Value))

)

I just wanted to add a fact:

If you have a division, that does not allow you to use the divisor "1" instead of "Nothing" you can still use the suggested solutions in this tread:

What you have to do is use your conditions twice: first your "old" way: IIf(Sum(Fields!divisor.Value) = 0.0, "", ...

Then in the dvision: ...Value) / IIf(IsNothing(Sum(Fields!divisor.Value)) Or Sum(Fields!divisor.Value) = 0.0, 1, Sum(...

As you can see, you still have a divsion by 1 implemented but it can never be reached as you ruled it out before.

That makes the renderer and you happy 😉