Ok.. let's redo the formula then, I don't know of a function that looks for the largest value that meets a certain criteria. So unless someone enlighten me, I will have to nest a few Ifs together:

=IF(D9="","",IF(AND(G9>0,G10>0),"",IF(AND(G9<0, G10>0), G9+E10, IF(AND(G10<0, G9>0), G10+E10, LARGE(G9:G10,1)+E10))))