You almost had it.

This
=SUMIFS(('D_Funding source document'!O:O,'D_Funding source document'!N:N, "2007")+('D_Funding source document'!R:R,'D_Funding source document'!Q:Q, "2007"))
should be
=SUMIFS(('D_Funding source document'!O:O,'D_Funding source document'!N:N, "2007")+SUMIFS('D_Funding source document'!R:R,'D_Funding source document'!Q:Q, "2007"))