.22 conversion unit AR

I'm not really familiar with blogs, but here goes. I bought a targetmaster .22 conversion at the July gunshow in Jackson. Does not work properly. shoots two to four times then fails to eject... always a live round in chamber and empty stuck in receiver or stove-piped. Shooting a Bushmaster ORC. Have tried three magazines and four types of ammo; and cleaned and oiled the unit. Any more suggestions? I guess I'll call the mfg. tomorrow