I have a question about shutter priority mode?

I thought I knew the camera but tried to shoot in Tv mode and couldn't get the slow shutter speed that I wanted. I'm away from home and don't have the manual. Can anyone lend a hand? I thought in Shutter priority mode, aperture and iso were automatically taken care of.

I can't get the slow shutter speed I want. Is there a limit as to how slow shutter speeds are in Tv mode?