QT help is not visible

Hello,

I have Qt 4.5.3 installed on my "D" drive.
I unstalled the QT from "D" drive and installed it on "E" drive.
After this I have modified all the environment variables.
My applications are getting build and I am able to see the output.
But I am not able to view any help messages when I press F1 for any QT object.
It is giving me message like "No documentation available.".
Also if I give a search in the Help menu it is not giving me the help messages.
Can anybody please help me how I can view these help messages?

Warm Regards,
Ganesh