I had a similar issue at first. The problem he has solved. It could be ROM your trying to flash is a cdma/gsm version, so in turn it didt know what img to use he fixed it to ask what one.
If not try forcing large img under settings, and keep screen on.
If not I would recommend email them. They very quick to get back to you. And can solve the issue. When. You email them, let him know what your running, what your trying to install, also attach the log.txt from SD/boot manager.
Hope it helps, it is a FANTASTIC app, GREAT SUPPORT
Sent to the third dimension from the 3rd.dimensional 3VO