Kingston and generic memory won't work

hey guys i bought a kingston 512 MB DDR 400 yesterday. i was so excited to try it in my coputer. but when i got home, i put the memory in my computer turned the power on and then…tooooot…tooooot…tooooot…aw crap :crying: …it didn’t work… i tried removing my old memory and use the kingston only and it worked…tried using them both in different slots and the no POST occured again. here’s the thing i noticed…my old memory is two sided but the kingston is only single…could it be the point of failure? because my old memory and the kingston have the same specs. they’re both DDR 400 512MB…my board is MSI K8N NEO 2 (939)…and my memory configuration there is 1T timing agressive and the rest is default…what d’ya think is the problem?