I think I saw fmradio in the Diablo repository applications list. I haven't tried it out, though, since I use MediaBox for the FM radio. Did you add a Chinook repository in the Application Manager? That could be a source of conflict.

Btw:
The FM radio is a standard V4L device (V4L=Video for Linux, a kernel interface for controlling TV and FM radio boards) on the N800 and I really wonder why there exist only 2 applications for controlling it.
There's even a Python module available for controlling the FM radio.