VOICE ACTIVATED TAPE RECORDERS?

I realize this may sound alittle lame, but who cares? if you know the answer....help. I just bought a memorex voice activated tape recorder from target, it was cheap, about 25 dollars, it takes 2 double a batteries and has a plug in charger. I put the batteries in properly AND plugged in the charger to the recorder AND the electrical outlet, but it still isn't lighting up or, seem to be working. If there are batteries in the unit, why do I need to ALSO charge it electrically....