ram trouble on a hp all in one

Kilobyte Kid

ram trouble on a hp all in one

Model #HP 19-2113w All-in-One 

 

i have 2 sticks of 4gb ddr3 pc3-12800 SODIMM 1.35v204  when i install both sticks it wont let my pc start up but if i remove one it starts right up and i have flip flopped the sticks back an forth in the slots and they both read just not at the same time any ideas  and i running windows 8.1  and i used the crucial scanner  to make sure it was suppose to be compatible