photo sensor and arduino

but when i put my hand over it to block any light, and i take off my hand, to show it light, there is no diffrence...

like it'll be on 406, and i quickyl cover i with my hand, and the next reading will be 402, and then i take my hand off and point it at a light, and i get 404, and then when i put it back down for a while it randomly changes to 358... there is no affect at all...