Should I send it back or am I just a Pentax Dummy??

[trotterbo]

I just bought a Pentax Program Plus camera body off EBAY. Looks like a well-taken-of body. I should say that I have worked for years with Konica SLR's and a RICOH KR30sp. I think I'm doing this correct .... but you never know. The camera came without batteries. I bought some 357 1.55V batteries. I had a Pentax SMC Pentax-A 1:4-5.6 35-80 zoom lens mounted on the camera. When I loaded the batteries apparently the self-timer switch was activated and the light on the front of the camera started blinking. OK, so far, so good. I tripped the shutter manually and heard it work. However, now I cannot get the shutter to trip at all. The film advance lever will advance the film frame-by-frame as evidenced in the film counter window. I have loaded film and the film is moving through the camera as evidenced by the rewind lever turning appropriately. Viewing through the viewfinder I can see the aperature setting change as I move the camera toward and away from light. BUT, still no shutter capability. So, I think the batteries are working, but I wonder if I have some switch set improperly. I hate to send it back, but if it's not working I will have to try. Any ideas ???? Thanks for any help, Bill Clayton