Try giving both battery posts a good scrubbing with a stiff wire brush. I've seen batteries with enough crud built up on the surface of the posts that even a brand new cable wouldn't conduct. Have you tried substituting a different battery? I've seen batteries with an internal open circuit that would show voltage, but couldn't flow any current. it's uncommon, but not impossible.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!