boot problem with ddr2 sdram

does anyone successfully port uclinux to nios board with ddr2 sdram?

i have a board with cycloneii and ddr sdarm, and when i run uclinux in ddr2 ram, sometime niosii ide uart jtag print: verified failed .It seems something is wrong with ddr2 sdram .does anyone know where is the problem? in addition , the ddr2 sdram can run successfully in other system.