Description
A. Can't Renumber
Common causes
A. For/Next and/or Def/FnEnd do not work
B. It's usually caused by having a DEF for a function without a matching FNEND. It could also indicate a problem within the defined function such as a multi-line IF that does have the END IF before then FNEND or a FOR.. NEXT loop where one or the other falls outside the DEF.. FNEND.
Common solutions
A. Find the missing For, Next, Def, or FnEnd and add it.
B. (same as A)
Notes
A. experience of JohnB. "Sometimes I have seen this error when trying to do the RENUM where saving the program first, then reloading it allows the RENUM to take place." - Dave Bohlke