Forget about those 2 variables, just create one instead.
p_ProductGroupandName =If(IsPromptAnswered([Product Group];"Product Group")=1 Or IsPromptAnswered([Product Group];"Product Nam")=1) Then (UserResponse([Product Group];"Product Group") + " - " +UserResponse([Product Name];"Product Name")) Else "PnL Total"
Thanks,
Mahboob Mohammed