Problem with DDR extension

Question

In my laptop "HP PAVILLON ZV 6000", i have replaced my DDR extension :
  - Nanya PC2700S - 25330 - 256 MB DDR - 333Mhz - CL2.5
By
  - Hynix PC2700S - 25330 - 1 GB DDR - 333Mhz - CL2.5
So I have :
  - 1 GB DDR in my extension part
  - 256 MB DDR in my principal part
But the computer doesn't start, the BIOS (it is updated with the last version) doesn't display.
My Motherboard is : zv6100.
What is the problem?

Answer 1

Did you try swapping the memory in the two slots? If I recall that model has one slot on the bottom for expansion and then an "internal" module under the keyboard.
Here is the Service Manual:
Manual
Page 5-31 shows the internal module. It should take up to 2 x 1gb of DDR 333 SO-DIMM so the only thing I can think is the 256 module is somehow not compatible with the 1 gb module.