Since the warning comes from the assembler and not the compiler the correct place to look for what it means would be the assembler manual. With that said it usually doesn't give much more details than the warning or error message itself which is Argument out of range. Least significant bits used.

See if Daves advice leads you to it, if not you're going to have to reduce the code until you find the offending piece or post the whole thing and perhaps someone is able to find the issue.

/Henrik.