Vostro 3250, ram not getting detected

I have a dell vostro 3250 with intel core i3, J4NFV motherboard and 4gb ram. Recently I thought of getting more ram in my PC so I bought a HyperX 8gb ddr3 ram. When I put the ram in my PC didn't detect the ram so I thought it was an issue with the ram and bought another HyperX 8gb ddr3 ram but that didn't work either. I think it's an issue with the compatibility of the PC. Please help if you can.