macbook and recording

Hi, my macbook doesn’t seem to recognise any recording I made, as the folders ‘audible’ and ‘record’ are all empty when I connect sansa via usb.  On the other hand, I am able to play the recorded pieces on the sansa itself.  So is this the problem with how I saved the recorded files? Or should I install some drive?  BTW the cd-rom that came with sansa is small, hence can’t be fit into my macbook.  Please advise. Thank you.