Using Festival or flite with Pi Zero

I’ve successfully installed Festival on a B+ using the on board audio - however when installed on the Pi Zero with a usb DAC I get the following error message “aplay: set_params:1087: Channels count non available” Any ideas to solve it would be appreciated.

Got it sorted out, it does work straight away on a fresh install, it must have been something in my setup upsetting it.
After messing about for a couple of weeks I finally found a workaround, then decided I had messed about with the image so much that a fresh image would be good, installed festival and it worked perfectly with no workaround!!