Sorry, I misunderstood.
There is the chance that you have a defective battery: Not un-heard-of with Lithium-Ion batteries. I would have a shop check the battery to see if that is the problem.
Also, is the new battery an Exact replacement from Toshiba, or an aftermarket unit by some other company? It could be the wrong battery. Since Windows can't see it when it is unplugged from the power-brick, it could be that the contacts on the battery are wired improperly.
If the battery checks out good, then the problem may be somewhere within your laptop.
---Forum members: Anyone else have some thoughts on this, please post a reply!