[U-Boot] problem with u-boot 2010.03

[nguen duy phuong]

Dear everyone 
i'm Phuong
 i living vietnamesepresent, i research chip's atmel (AT91SAM9260) and i want to install u-boot on chip AT91SAM9260 but i have some problem with it, so that i need help from you 
this is my step build u-boot:
step 1: 
i configure it for chip AT91SAM9260 technical information:   
Basetext :21f00000   
set At45DB041D 0x1C   
Bus with sdram to 16Bits
step 2: 
i build it with gcc,toolchain  
make 0=/tmp/build distclean  
make 0=/tmp/build at91sam9260ek_dataflash_cs1_config  
make 0=/tmp/build all
step 3 : i open samba v2.9 in windows   
i puts bootstrap v.1.5 in 0x0  
i puts u-boot.bin in 8400
final: i'm reset my board but i get cksum bad. 
i don't understand it. can you help me ???

note: i use linux OS(ubuntu 9.04)
 
I am looking forward to hear from you soon