|The density or clock speed may be wrong. Go to crucial.com and use their online configurator to see what RAM is compatible. Laptops can be fussy about what RAM they can use. Below is what HP states you can use:|
256 MB (266 MHz) DDR SDRAM (256 MB SODIMM in slot 1) or
512 MB (266 MHz) DDR SDRAM (256 MB SODIMM in slots 1 and 2)
If you bought 333 or 400MHz RAM it may or may not work. If the density is too high the laptop may only recognize half the RAM.