Sounds normal to me; you're putting the camera on aperture priority, the "Auto" you refer to, with a lens cap on the lens. In the A setting the camera is waiting for enough light to complete the exposure. But , with a lenscap on (not too mention f22)the meter isn't sensing enough light. Try this , start the exposure as you have been with the cap on...take the cap off and I bet the shutter will close.