Replacement coil won't work

I have a 97 Jetta GL 2.0 automatic. The coil is cracked all over the place and it runs like crap every time it's wet out. I've put silicone on the cracks to try to seal it up, but it really needs to be replaced. I have now tried 4 replacement coils, each from a different manufacturer, and none of them have worked. I put the old coil back on and it fires up. I haven't tried the OEM part yet but will order it next. Can anyone tell me what's going on? It's driving me a little bonkers.

Thats quality aftermarket parts for ya... makes you wonder why there 1/2 the price..