All vvfls/positive but not clear blue digital why?

Hi All if my tests have vvfls and this first response digital says pregnant but not this clear blue digital at the bottom but i'm confused cause it says i can take it four days before missed period and i am two days out from my period, could anyone help me understand why? is there a chance i'm not pregnant? I thought the clear blue would catch it since I am 2 days till AF?