Let's do a test.
Remove the slide from the pistol, then hold the receiver(frame) and pull the trigger. If the trigger moves freely without engaging the hammer, pull back slightly on the hammer until you hear a click. If it clicks, the trigger-bar has engaged the hammer. If NOTHING happens, push down on the part of the Trigger-bar that peaks out the side of the frame. Is it "spongy"? Does it move down about an eighth of an in and spring back up?
Beyond this, it's real hard to say without seeing the pistol. If you don't solve it after this post, remove the slide and take pics of the trigger-bar etc. in the frame and post them so that we can take a look.