Inspiron 3512: Top ram slot not allowing to fit in fully

I've recently bought a 4gb ram stick so I could upgrade the four that is already inside my laptop, and make it 8gb. I ran into a little problem though, because when I had tried to stick the ram in, it wouldn't fit in all the way, and I couldn't push down to secure it. I tested the ram with the slot below the top one and it worked. Both ram sticks work, but I don't understand why I can't put the other stick on the top slot.

I'm writing this with the new ram I had bought, so I know it works. I tried the original ram that came with the system on the top slot and that couldn't even be put in. The gold pins show and the little cut on the gold pins, it doesn't go in all the way

This is the original ram stick