Can any one tell me what the following error message means

"Compile error in hidden module: Addition"

The macro transfers values from text boxes and inserts into various
cells after scrolling down to find the first available empty cell

The macro was written with the aid of "Macros for dumbies" and I'm a
complete novice so there are probably errors all over the place, but
the macro has been working for about a year and then suddenly stopped
working

Thanks in advance