My african fat tailed gecko isnt eating?

i have had her for 3 days know i gave her a cricket the first day now i didn't see her eat it but it wasn't there any more and it looks almost impossible if you were a cricket to jump out of the cage/tank thing. so i put another cricket of relative size in there for her to eat and it sat there for a whole day and she didn't eat it. now i know she is a nocturnal (that what the guy at the pet store said) so i umed she was gonna eat it at nighttime and she did not. the only thing i can think of is that i know snakes and stuff don't eat on a daily basis if they don't move around A lot and my gecko didn't move around a whole lot yesterday.