Bad memory stick?

I just bought 256mb of pc2700(333mhz) to put in my k7s5a (sis735)mobo , but the thing wont POST. Here are a couples of things i tried:

Put the stick in different slots.
Clear CMOS
Update the bios.
Boot with my old PC133 and put all the memory settings to safest and then use the pc2700.

None of this worked.
Now , before i return it , is there anything else i could try?
Also , could this be a compatibility problem? The memory is Samsung and on the chips its writen "Samsung 214 , k4h280838D-TCB3"

I just took a look at the motherboard manual, and Samsung RAM was not one that was tested and verified to work with your motherboard. Perhaps that is the problem.