The official forums is where it's at. But this is a common problem, try this:
1.On your windows machine click on start and in the (Search for programs and files) box type in regedit and open regedit.exe
2. Next click on the little arrow next to the folder named HKEY_LOCAL_MACHINE and make your way to ergc directory the full path is
HKEY_LOCAL_MACHINE -> SOFTWARE -> Wow6432Node -> Electronic Arts -> EA Games -> Command and Conquer Generals Zero Hour -> ergc
3. Click on the ergc directory and right click on Default (located on the right side under Name) and Modify it.
4. Now simply add the - between the serial numbers.Write it exactly how its written on the game you bought. if you notice It only displays your serial number without the - between the code so you will just need to add them in
for example change it from 123A5678B8CDD3D3P0P0 to 123A-5678-B8CD-D3D3-P0P0 now try playing the same you should be able to play it online.
If it doesn't work then come to the official forums and make another thread there.
