nand createbbt fail .

i have micro2440 board 7" 256MiB nand flash.

i have loaded u-boot is ok
i have execute nand scrub is ok
i have execute commande nand createbbt and fail,it wait along time with the
line display as below

Creating BBT. Please wait ...Bad block table not found for chip 0
Bad block table not found for chip 0

any idea ?

it seem is ok now is because time is long.

Ya, the 64M board takes about 30 seconds so, yours could take about 2
minutes.  Time to geta cup of coffee!