[U-Boot] sam9x5 can't find Nand flash

[alex]

 Hi MAINTAINER:
  Now I develop our product based on sam9x25 EVK, and redefine our NAND partitions. I set u-boot environment in flash address0x80000.
if "saveenv" and "reset", u-boot will print "can't find NAND flash". If I set u-boot environment in the address 0xc0000 as EVK board, it's OK. I cant' know the reason.

Best Regards,
Alex