nested formula HELP!!

[Mellb]

I don't know if this will work but I have the following function which works fine but I want to return a 0 instead of N/A if there are no matches, formula is as follows:

=IF(G13="actual",vlookup(A15,'data input sheet'!A17:ES56,8,false),vlookup(A15,'data input sheet'!A17:ES56,9,false)

any suggestions would be greatfully appreciated as I have been trying to make this work for hours and am starting to tear my hair out!!

thanks

Mel.