Ram Upgrade = No signal

I've got an emaxx mobo with NVIDIA GeForce 6150SE, Athlon X2, 1x1gb RAM.
I bought a 1x2gb RAM then installed it on the other slot along with my 1x1gb RAM (I'm hoping to get a 3gb RAM for graphix and photo editing) and I get no signal on the monitor. The power button illuminates, the fans are spinning, and the dvd drive lights but no beep sound. When I removed the 2gb RAM it works and boots normally then I replaced 1gb Ram with the 2gb RAM it works and boots. What do I do next?

Sounds like mis-matched ram at different speeds !

Download CPU-Z to test each stick individually for Mfg & speed.

So you've eliminated the possibility of a dud memory stick by trying them individually. Apart from their capacities, do the specifications and timings of the sticks match? Could it possibly be a faulty slot on the motherboard (try it)?

just found out they have different DRAM frequencies. The 2gb RAM is 400MHz and 1gb is 667MHz. Guess there's no other way out of this.
Thanks for the Help.