It hass been a while, but When I used the G49 function it only was for 5 axis. I also seem to think that they way you are calling it up is wrong. I also believe it goes into incremental movement with the G49 command. Let me see if I can find an old post. Ohh wait.
Try that.. I would expect it to be incremental so be prepared if you have something prepared in absolute coordinates.
BTW how are you getting the extra palne, or are you trying to cut on a surface at a angled surface at a controlled depth?