BeagleBoard Booting

Hi,

I used the code below to boot BB Xm, It worked well. But I'm using
that code everytime while booting.
Some parts of code which I marked with x doesn't work. What should I
do ?

x mmcinit
x mmc init
mmc rescan 0
fatload mmc 0 82000000 MLO
x nand unlock
x nand ecc hw
nandecc hw
nand erase 0 80000
nand write 82000000 0 20000
nand write 82000000 20000 20000
nand write 82000000 40000 20000
nand write 82000000 60000 20000
fatload mmc 0 0x80200000 u-boot.img
x nand unlock
x nand ecc sw
nandecc sw
nand erase 80000 170000
nand write 0x80200000 80000 170000

Thanks