mini6410 : how to relocate NAND to SDRAM

Hi every body.
I try to developed mini6410 with No OS, but i have a problem with booting
from SDRAM.

I believe at power on reset the hardware will copy 4KB of NAND flash to its
STEPPING-STON (locate in 0x0C000000) and the code will Pursue from address
0x0C000000.

In these case i developed a code to copy whole of the NAND flash to the
SDRAM(locate in 0x50000000) but i can't direct Program-Counter to the SDRAM
to run my program. however i'm sure my code has written in SDRAM address
(0x50000000).

in additional my RO compiler setting (linker options) set to 0x50000000.

i really thankful if some one help me.