Sometimes, the graphical tracer (enabled with guitracer/0 or started using gtrace/0) highlights a call (the green area) incorrectly. If it shows a completely different goal than you expected you may be wrong in your expectations or there may be a bug in the debugger.

If the green area doesn't exactly highlight a goal, it is possible that you are using a POSIX (Unix, Linux, MacOSX) platform and the file has been transferred from a DOS (Windows) platform without updating the file to the POSIX newline conventions. I.e. your file contains CR/LF between lines while POSIX systems expect a single LF character.

The built-in editor can tell you this. If you are in the tracer, type ^X2 (that is Control-X followed by 2). This opens a full editor window. Then use the mouse to select File/Properties. This opens a window that shows (among others) the encoding of the file. This field says either NL=posix (ok) or NL=dos (wrong). In the latter case, use a tool to convert the file. Most Unix platforms ship with dos2unix for this purpose.