Thanks Bjorn,

I had to edit the formula a bit since the Swedish version is a bit different from the Belgian one that we use.

In our Belgian version the correct formula is If(C3=0;#N/A;C3*D3)

Furthermore, although the line will no longer be visible in the graph, there will still be an ugly "#N/A" visible in my data. This I remove by using a Conditional formatting : Formula is =ISERROR(B2) and say that the format to use is a white background. That way the white background will hide the data.

Thanks again for your help