[U-Boot-Users] Nand flash problem

Hi, I m giving support of a 32MB Nand from STMicroelectronics in the u-boot.I have added the manufaturer id and device id in the list of the already supported device.The device is recognised successfully by the u-boot.But the problem is that It shows all the blocks as the bad block and not able to read and write on the Nand.While the Nand is working fine if I used the driver of the kernel after booting the kernel with the Help of the debugger I,e nand is not defective.Can anyone pls tell me what can be the problem.

Thanks Bye