"Device not responding" for OHCI controller

Hi,

I am developing a USB stack on OHCI controller.The target environment is MPC5200B.

The code behaves properly and enumerates the LS (Low-speed)devices perfectly.I am able to communicate with the keyboard.

But if i plug in any FS/HS (Full-speed/High-speed) device I get "device not responding" error on get descriptor request . I tried toggling the speed 'S' bit in endpoint descriptor structure , but with no effect.

Can any body let me know what is the problem?

Regards
Siddharth