How do you get two sumif's together? Example attached

Hi Guys,

Can someone please help me with this little problem I have been having?

In the attached file I have a spreadsheet whereby I need to link data from the overheads tab to the summary tab. I need to link the nominal code in column A of the summary tab and the month in row 3 to pull data from the same info in the Overheads tab. I need it to pull the sum of the corresponding data. I hope this makes sense, if not please let me know and I will try to explain again. It seems like it is two sumif formulea put into one however I just cannot link them. In cell D11 I have tried to do my own version however it is clearly not working...

Any help would be greatly appreciated

Thanks

Gurd