The voltage seems fine, but I'm going to ask you to charge that battery anyway just in case. Then retry.
Using your multi-meter, double check the connectivity of your wires, making sure it's all solid.
It worked before, and then you said it sometimes worked and sometimes didn't. It could be a wire was slowly breaking. Check to make sure the wires look ok.
ps - posting is best, as it allows other people to chime in their thoughts and search for this info online