bkay

Could you have the bobbin case in there wrong? That little "finger" on the top of the bobbin case has to fit in the slot. It "sort of" clicks when it goes in place.

Another possibility could be it's the wrong bobbin case.

Past that, I'm no help.

bkay

edit: What do you mean, it won't sew? It won't make a stitch? Or the needle won't go down? The needle goes down, but doesn't pick up the bottom thread? Exactly what is it not doing?