Can't mux .m2v vid with .m1a audio

[bllx]

I have 2 files, a .m2v video track (which I applied pulldown to), and an audio track for the movie .m1a
Both files play fine in VLC and are identical length. The .m1a audio file is reported in VLC get info as an mpga file.
I want to mux em back together for a DVD burn, but ffmpegx refuses; it claims the .m1a format is unknown.
Any suggestions how to mux these two files so I can burn a DVD from em?

Thanks
bllx

[Case]

The mux tool wants the MPEG audio to be named ***.mp2, so rename the 'm1a' part to 'mp2'.