The new compiler does a better job of checking for consistency of arguments, if you specify the /warn option.
In the case of NLPQL and its variants, the function value F is sometimes a scalar, sometimes an array of size 1. Strictly speaking, this is an error, but one that has no adverse effect with most compilers.
Either do not use the /warn option when you compile, or change F to F(1) in the declarations and expressions that contain the variable F.