Library /sys$common/syshlp/basichelp.hlb Compile time errors, ILLCALFUN  *Conan The Librarian (sorry for the slow response - running on an old VAX)

  ERROR - You attempted to use the CALL statement  to  invoke  either  a
  DECIMAL,  HFLOAT,  or  STRING  function.   Invoke  the subprogram as a
  function in an expression.