Upgraded RAM, now has multi-colored horizontal lines then crashes

MacBook Pro Mid 2010 13" Unibody I'm trying to upgrade from 4GB RAM to 8GB RAM. I bought two 4GB sticks from iFixit, followed the iFixit install instructions, and upon restart, it appeared as if the swap had worked. Going into About tab I can see that the computer is recognizing the new sticks, but shortly after starting the computer, horizontal colored lines filled the screen, the computer froze, and then shut off. I tried turning the computer back on, but couldn't make it past the log-in screen before the lines showed up again. I took out the new RAM sticks and put back in the old 2GB sticks, and this fixed the issue.

Any ideas on how I can upgrade to 8GB successfully? Is there a step that I am missing?

I am in a pickle here; I need to upgrade to 8GB since one of my school's software programs is no longer working on my computer, since their last software update. I was told that Lockdown Browser now requires 4GB of available RAM in order to facially recognize the test taker. :(