■ You used "FN" as the first two letters of a SUB procedure
  or variable name.
 
■ "FN" can be used as the first two letters only when calling
  a DEF FN function.
 
■ Possible solution:
 
  • Rename your SUB procedure or variable.
 
■ If you need additional help, move the cursor to a keyword
  and press F1 to open the Help window.