A:Answer Are U sure the UBS connector is fully pushed in? It should go in with a 'thumb-type' push. If this isn't the problem, is the battery at the bottom of the mouse flashing red? If not, that's the problem. If it is flashing red, did U by chance drop the mouse? That's what caused me to replace my old mouse - too many 'hits' on the floor. If none of this works, take it back to Best Buy with your receipt as they have a 90 day guarantee on their products. Leon