[alsa-devel] Trigger problems while writing Alsa Shim

I am writing a shim from alsa to our own sound card drivers. I was able to get the init driver working and our sound card recognized. Things seem to be set up correctly. When I do aplay to my device (USB device works find), it calls my copy callback twice and then it calls the trigger and fails. The call that fails is in pcm_write (writei_func) with a -5. I know that my callback returns zero but there must be something else under the covers since that gets to be zero. Any help would be appreciated. T