Problem with Apogee Duet on Ipad

Hi
Mi ipad 3 is connected with the apogee Duet for Ipad ans it works pretty fine with all the apps like Cubasis, Ampkit and the another except Ireal pros I'm unable to play the sheet through the Duet line out.
When I push play bottom it began to play the first chords but immediately the sound is hashed with repetition of chords and finaly stop.
It looks like a buffer issue, but I don't know how to fix it.
I read the post about the Apogee jam trouble and I try to use it with audio bus and Ampkit but the problem still remain
Thanks for your advise