Changed battery, but MacBook Pro won't charge

I just changed the battery on my mid-2009 macbook pro, but it won't charge. The battery came with a 50 percent charge. The magsafe light stays red and the icon in upper right corner says it's charging, and even shows "time remaining". But as I keep using it, the battery is drained percent by percent without adding any power to its storage (no I'm not running anything intensive). I did already reset the SMC a couple of times. Any ideas what might be the problem? Thank you in advance!

Thread moved to more appropriate sub-forum. Not a "Schweb's Lounge" topic.

Thanks,

- Nick

Is the battery not charging issue why the original battery was replaced, or is this a different problem?

Hmm, I seem to have this problem except my mag-lock charger stays green and it actually shows it is not charging, changing plug sockets or taking it out for half an hour or so solves it most of the time!

Hope you can fix your mac.