Im not sure if my digital multi tester's battery test function is working.?

i just bought a digital multi tester w/ battery test function for 1.5v and 9v batteries. everytime i try a working battery ( i know it is working coz im using it) it just indicates three zeros "000" what does that mean? is my tester working? if a tester is working what's a good battery and one that needs to be charged supposed to read?