11.10 - Unity 3D does not work on Dell system with a AMD Radeon HD 6470M

I am running 64 bit Ubuntu on Dell with 1GB graphic card.

I login with "Ubuntu" hoping to see Unity 3d but it doesn't. Unity 2D runs instead. when I type in

echo "$DESKTOP_SESSION" 

it confirms the Unity-2D.

I've checked the System info that shows like :

The graphics row shows itself as empty. SO I've presumed that the graphic drivers aren't detected and hence I went to Unity-> Additional Drivers and installed the fglrx driver that the UI has suggested.

Even after installing so, the graphics part in System info details shows nothing and still Unity 2D runs in spite of all the effort.

Please help! How can I get my Unity 3D back?

Hardware Info

Video Card : AMD Radeon™ HD 6470M - 1GB (For ICC)

RAM : 6GB (1 X 2GB + 1 X 4GB) 2 DIMM DDR3 1333Mhz

OS : 64 bit Ubuntu 11.10

Edit : Output for /usr/lib/nux/unity_support_test -p

X Error of failed request:  BadRequest (invalid request code or no such operation)
  Major opcode of failed request:  155 (GLX)
  Minor opcode of failed request:  19 (X_GLXQueryServerString)
  Serial number of failed request:  21
  Current serial number in output stream:  21

Finally got this resolved myself.

Firstly, I've removed all traces previously installed graphic drivers/fglrx drivers provided by Ubuntu. After doing so, I've re-installed open source graphic drivers instead. Everything is back to normal.

Just in case if anyone else is experiencing the same headache, you can take a look at the below link. I've described in detail, the complete struggle and the steps to resolve it in this blog post.

http://nerdysermons.blogspot.com/2011/11/solve-graphic-driver-errors-unity-3d.html