Isochronous transfers not supported

hi,

Recently,a problem always troubled me,but I had no idea about it.Would you please help me!

A uclinux system had been tramsplanted successfully into the development board DE2,and some common USB device were supported including the USB camera.

After booting the system on the board,the camera was detected ,and the camera device filesystem was generated in the directory:/dev/v4l/video0. In the kernel the isp1362-hcd and video4linux support and other options were choosed.

When I use this funtion to open the camer device,a problem was generated:

the function is int fp=open("/dev/v4l/video0",O_WRRD);

the result is: Isochronous transfers not supported ..........init isoc: usb_submit_urb(0) ret -28

the return value of fp is fp=-1;

That's to say the camer device can't open,wheher the isp1362 driver(isp1362.c) or the ov511.c had problem?

I wondered that in the isp1362.c there are funtion to suppot isochronous ,but why the system display " Isochronous transfers not supported "

why ,would you please help me!!!