AFAIK, regular microphones don't need any power, as the coils in them generate the power when they pick up sounds (vibration of a piece of metal inside a coil).
Why it doesn't work? Hmm it could be in the connectors, or maybe you're using a mic that's out of your sound card's specs and your soundcard prevents it from working (that last doesn't sound all that realistic, but it could be possible).
What to do:
1. test your new mic on another device (computer, cassette deck, mixtable etc)
2. test your adapter plug
3. compare your mic's specs with your soundcard's specs
4. report back