word and long access of SDRAM

I am working with samsung 2410 and k4S561632A 256M SDRAM 
we are using SDRAM only as 128M
With trace32 we have confirmed word access of SDRAM works right.
Setting display format as 16 bit and writing word at trace32 termial
works right.
But when we set display type long, and writing 32 bit data, it fails.
Lower word is repeated in upper word. but we have anyway succeeded in
word access, we have passed the situation.
But when I have download bootloader and debugging, I have found 32 bit
instruction in SDRAM displays same situation. lower word of
instruction is same as upper word. and CPU malfunctions.
code in flash works right.
I have no idea why this situation occurs. I even have no idea if this
is h/w or s/w problem.
I have tried some memory controller setting, but it remains the same.
Please let me solve this problem
thanks.