VMS Help CC, Messages, NEEDNONVOID  *Conan The Librarian (sorry for the slow response - running on an old VAX)

 Message        <Context> "<expression>" has void type, but occurs in
                a context that requires a non-void result.

 Description    An expression that must not be a void type was void.
                For example, the control expression for an if
                statement must not have void type.

 User Action    Modify the expression so that it has the required
                type.