I bought a new mag for my P22 today and the gun will not work with it. It fits perfectly and will load a mag when I pull the slide back, but the trigger will now function with it in the magwell. I removed the mag safety and it still does the same thing. My other 2 mags work fine. Looking at the mag it looks almost identical to the others. the only differences I can see or, on the sides the slots towards the top of the mag or smaller and the small slot on the front is below the 2 bulges instead of on top. The funny part is the number on the is 265 93 44-A which is exactly what is on the mag that came with my gun. It is a factory Walther mag. Here's a pic of it, it is at the bottom under the ammo.
edit: if it's not a simple fix I will try to go back to the gun show and see if I can exchange it.