One of the crazy aspects of RAM sticks is that you need the sticks to be identical. Since the old stick is unlikely to be found, try this. Using only the new stick, does it work? If not, it's the wrong stick.
If it does work, get one more of that stick. But that's usually not enough. There are over a dozen parameters to these sticks and I no longer do that work. But I do head to Crucial.,com to order 2 sticks and 99.99% of the time it works. (actually it's been 100%.)
I have been messing with this for a while and I need to enlist some help. I bought this laptop off of craigslist and it came with a 1 slot 4gb of RAM. I wanted to add an additional 4gb of RAM. I looked into manuals and looked at everything I could before I made my purchase. I purchased exactly what they tell you to, but when I install the new RAM, and power on the laptop, I am given a blank screen, no BIOS, no beeps, Nothing. Even the GPU fan stops spinning, but everything else seems to be on. I tried updating BIOS, but Dell only offers the ancient ones on their site and I don't know where else to get my BIOS from. Please help me! I have tried just about everything and I don't know what to do. I have also gone into BIOS and looked for memory configuration, but it seems to be pretty locked down. Any suggestions please!