Question of writing data to SD_card

Hi All,
i'm trying get the LM4f232h5qd to save some data into sd card. In the SD_card example, it used ROM function to set UART port. And I use function without ROM to set my SSI interface. For example,
ROM_SysCtlPeripheralEnable(SYSCTL_PERIPH_UART0);//set UART port
SysCtlPeripheralEnable( SYSCTL_PERIPH_GPIOD ) ;// set SSI interface

However, the SD card can work successfully, SSI interface can't. Is the ROM function and without ROM function can't work together? Or in this case, what I should notice?

Any help would be greatly appreciated!

-Unis