Interesting, I couldn't get the command line to work either. Even though it says how to do it in the help file.
Well, here's a couple alternatives.
In the same folder as mpasmwin.exe, open the MPLAB.INI file and modify or add this line.
CaseSensitive=OFF
-- or --
Start the MPASMWIN program directly by clicking on it in windows explorer, or type MPASMWIN from a DOS window.
Unselect the "case sensitive" checkbox then click "Exit".
Then try to compile again.
HTH,
Bookmarks