Wrong Image Format for bootm command ---SD-BOOT DM365

Hi all I used “dm3xx_sd_boot-6.1” tool to burn UBL,U-BOOT and kernel into DM365-IPNC，UBL,U-BOOT can run normally，but u-boot can not boot up the kernel，the debug info. as following： I2C: ready DRAM: 256 MB NAND: NAND device: Manufacturer ID: 0xec, Chip ID: 0xf1 (Samsung NAND 128MiB 3,3V 8-bit) Bad block table found at page 65472, version 0x01 Bad block table found at page 65408, version 0x01 128 MiB *** Warning - bad CRC or NAND, using default environment In: serial Out: serial Err: serial ARM Clock :- 432MHz DDR Clock :- 340MHz Ethernet PHY: GENERIC @ 0x01 Hit any key to stop autoboot: 0 Loading from NAND 128MiB 3,3V 8-bit, offset 0x400000 ** Unknown image type Wrong Image Format for bootm command ERROR: can't get kernel image! Then I use tftp download the same kernel again >tftp 807000000 uImage;nand erase 400000 500000;nand write 82000000 400000 500000 after power on,U-boot can boot the kernel,debug info as following: I2C: ready DRAM: 256 MB NAND: NAND device: Manufacturer ID: 0xec, Chip ID: 0xf1 (Samsung NAND 128MiB 3,3V 8-bit) Bad block table found at page 65472, version 0x01 Bad block table found at page 65408, version 0x01 128 MiB *** Warning - bad CRC or NAND, using default environment In: serial Out: serial Err: serial ARM Clock :- 432MHz DDR Clock :- 340MHz Ethernet PHY: GENERIC @ 0x01 Hit any key to stop autoboot: 0 Loading from NAND 128MiB 3,3V 8-bit, offset 0x400000 Image Name: Linux-2.6.18_pro500-davinci Image Type: ARM Linux Kernel Image (uncompressed) Data Size: 4264296 Bytes = 4.1 MB Load Address: 80008000 Entry Point: 80008000 ## Booting kernel from Legacy Image at 80700000 ... Image Name: Linux-2.6.18_pro500-davinci Image Type: ARM Linux Kernel Image (uncompressed) Data Size: 4264296 Bytes = 4.1 MB Load Address: 80008000 Entry Point: 80008000 Verifying Checksum ... OK Loading Kernel Image ... OK OK Starting kernel ... Linux version 2.6.18_pro500-davinci (root@localhost.localdomain) (gcc 鐗堟湰 4.2.0 (MontaVista 4.2.0-16.0.32.0801914 2008-08-30)) #1 PREEMPT Wed Mar 28 15:11:57 GMT 2012 what's wrong with it? thanks!