The detector program from AMD can't pick up the card, neither can the last installer with the most recent drivers for the GPU, and windows update still considers the drivers that were the latest when I updated to windows 8 are still the latest even though the AMD site shows a later version (and I think this is because the update from 7 to 8 mucked up the ID for the GPU rendering it unable to be detected by any of the vendors software).
Your laptop wouldn't happen to be a Dell would it? There are some laptop vendors (like Dell), that have an agreement with AMD and nvidia to only allow drivers from the laptop vendor's site to work.
I know this because I have a Dell Studio 17 laptop. Dell provides drivers for the Radeon GPU of this laptop on their website. AMD also provides drivers for the same GPU on their website. However, because of an agreement between Dell and AMD. Only the driver installer from Dell works. Not good since AMD has newer drivers than Dell. I think this GPU uses either vendor or hardware ID specific to Dell. Something like that anyway since the AMD drivers somehow detect my system configuration and will not install the display driver.
It's actually an acer laptop, and when I got it the GPU was identified in the device manager as ATI Mobility Radeon HD 4250, but once I upgraded from windows 7 to 8 it was identified as ATI Mobility Radeon HD 4200 Series (Microsoft Corporation - WDDM v1.1).
There's also no windows 8 support for this laptop from acer as the driver lists stop at windows 7 (although some of the drivers that are being used are the original ones, and I'm not certain if there's any lock out for the GPU driver install.