New battery will not charge but has good life?

So, I just got a new ifixit battery for my iPod video. Replacement was successful, and iPod turned on as soon as everything was hooked up.

But, now it won't charge. It is not shutting down immediately like a lot of other people report with their iPods. It is slowly running out of battery life like any battery would, not particularly slow or fast. But, when I plug it in it doesn't recognize it's charging and the battery doesn't seem to charge at all.

It is able to sync to iTunes without a problem, so there isn't an issue with the cord I'm using or the plug you put the charger/cord into (not sure what you call that).

Any suggestions? I'm not sure if I got a defective battery or need to replace another part. Anyone else experienced this?

Thanks!