New 2GB memory module doesn't work in slot/bank 1
Bought a 4GB kit from Crucial (CT25664AC800) to replace my current 2x1GB modules. After installing it, my computer doesn't boot up and starts to beep right after I turn it on. It makes three consecutive quick beeps.
After some trial, I isolated the problem to be in memory slot/bank 1. The only memory that works in that slot are the original 1GB modules. All combinations of configurations work except configurations that include a new 2GB module in slot 1.
I'm sure that I'm properly inserting the module in the slot. Original modules work on first try and I already cleaned the slot with a contact cleaner and a tooth brush.
Please advise, I don't know what to do right now, Crucial says that if both modules work in slot 0, then the problem is in the slot or that I'm not seating it properly.