Hmmm
Your GPU hardware does support DX11
But it looks like Windows 7 has a bug where some GPUs report the incorrect DDI version
Things to try:
- Install this hotfix for windows 7 that "apparently" fixes the issue
- Install/Reinstall the latest device drivers for your GPU
Your GPU may simply be too old however - it was released in 2010 and ATI stopped providing driver updates in 2013
Be careful when applying windows updates or installing new drivers - always backup first.
Good luck!
Aaron