Cubasis with iPad and Audio interface

I am trying to record audio (guitar and vocals) onto Cubasis on IPad 2, using a Focusrite 8i6 audio interface, but no signal is being received. I have loaded the 8i6 iPad mappings, and the 8i6 sends a signal into GarageBand satisfactorily, but not into Cubasis. Is there compatibility issue, or are there some settings on my audio interface or in Cubasis which I need to adjust? Any help much appreciated.

Problem sorted, with thanks to Focusrite Technical Support.