Unity 4.6 failed on installation

Hi,

I just downloaded Unity 4.6 for my mac osx 10.5.8. When I tried to install it, just gave me a message saying Installer Failed. Is this version not supported on my osx? I did not see any requirements anywhere. Please help me with this issue.

Thank you

http://unity3d.com/unity/system-requirements

Mac OS X 10.6+.