Compatability Allow DirectX9?

I was told my someone in order to get one of my games to work is to go to the game .exe file and right click, Properties and Compatibility and to check off the box Allow DirectX 9, but I don't see it..
thanks

What game are you having problems with?, and as far as I know there is no such option for doing that, Vista although using DX 10 also can use DX9 at least that is as far as I know.

More information would be more helpful if you can :D

If you haven't yet update your DirectX,

http://www.vistax64.com/gaming/162064-latest-directx-update.html

It will update the DX10 files and update/add any missing DX9 files.