Avoiding the #Value error

[erin-5304]

I have been trying to get rid of this error but can't figure out where the error is.

=IF(C59="WW-1",Flat Rate,IF(C59="WW-2",Flat Rate,IF(C59="WW-3",Flat Rate,IF(ISNUMBER(F59),SUM(E59*F59,"")))))

[#2]

@erin-5304 

You're missing some quotes around Flat Rate.

The formula can be shortened to

=IF(OR(C59={"WW-1","WW-2","WW-3"}),"Flat Rate",IF(ISNUMBER(F59),E59*F59,""))