Problem in WinCE 6.0 USB Composite Driver

I am Porting USB Composite Driver in WinCE 6.0,

I am using Two Composite Client Device(Composite Driver Child Device)
1. USB_Serial Client and
2. Mass_Storage_Device Client

I can able to get the Mass_Storage_Device, but I am facing problem while
using Activesync, when i Connect the USB Client Cable of the WinCE Device to
My PC, initially it is detecting the ActiveSync after 10 seconds it is
automattically getting disconnected with Error Message

AUTORAS:: Dialer notifies: [2] [Dialer Terminate]
Endpoint Zero FAILED SETUP udccsr=0x90. Sent STALL

But i can able to get both working when i do like this:
1.Disabled ActiveSync in PC.
2.Connected the USB Client Cable of Win CE Device to PC.
3.After the Mass storage Device mounted ,i have enabled the ActiveSync in PC.

In this case i am able to get both working, but

Why it is(Activesync) getting Terminated, when both(mass storage &
Acitvesync) are working simultaneously?

Please help me in solving the issue.

Thanks in advance.

sarathy
Wed May 07 08:06:00 PDT 2008