OMAPL138 boot with UBL "No magic number found"

Hi,

I want to use ubl copy the U-Boot in OMAPL138.

I only change the DDR2 parameters in OMAP-L138_FlashAndBootUtils_2_40 and compile.

But when I download the sft_OMAPL138_SPI_MEM.bin into SPI Flash.

The UART print as follow:

OMAP-L138 initialization passed!
Booting TI User Boot Loader
        UBL Version: 1.65
        UBL Flashtype: SPI
Starting SPI Memory Copy...
No magic number found.
Looking for: 0x55424CBB, but read 0x41504954.
SPI Memory Boot failed.

I don't know much about the UBL and what is magic number ,someone help me?