cannot execute SSIConfigSetExpClk

Dear TIVA Users,

i'm trying to configure the SSI2 port for using SPI.
the weird thing is, when execute SSIConfigSetExpClk he hangs.

He wont reach my puts("test");

this is the code i'm using:

#include <stdbool.h>
#include <stdint.h>
#include "inc/hw_memmap.h"
#include "driverlib/gpio.h"
#include "driverlib/pin_map.h"
#include "driverlib/ssi.h"
#include "driverlib/sysctl.h"
#include "driverlib/uart.h"
#include "driverlib/rom.h"


int main(void)
{
	uint32_t data;

    //config clock
    SysCtlClockSet(SYSCTL_SYSDIV_1 | SYSCTL_USE_OSC | SYSCTL_OSC_MAIN |
                   SYSCTL_XTAL_25MHZ);


    //enable peripherals
    SysCtlPeripheralEnable(SYSCTL_PERIPH_SSI2);
    SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOG);
    SysCtlPeripheralEnable(SYSCTL_PERIPH_GPION);

    GPIOPinConfigure(GPIO_PG7_SSI2CLK);
    GPIOPinConfigure(GPIO_PG4_SSI2XDAT1);
    GPIOPinConfigure(GPIO_PG5_SSI2XDAT0);


    SSIConfigSetExpClk(SSI2_BASE, SysCtlClockGet(), SSI_FRF_MOTO_MODE_1,
                       SSI_MODE_MASTER, 100000, 8);

    puts("test\n");
    //
    // Enable the SSI0 module.
    //
    SSIEnable(SSI2_BASE);

    //configure ss pin
    GPIOPinTypeGPIOOutput(GPIO_PORTN_BASE, GPIO_PIN_0);


    //set SS low
    GPIOPinWrite(GPIO_PORTN_BASE, GPIO_PIN_0, 0);

    uint8_t i;

    puts("start loop..\n");

    for(i = 0; i < 100; i++) {

		SSIDataPut(SSI2_BASE, 0x03);

		while(SSIBusy(SSI2_BASE));


		SSIDataGet(SSI2_BASE, &data);

		while(SSIBusy(SSI2_BASE));

		puts(data);
    }

    GPIOPinWrite(GPIO_PORTN_BASE, GPIO_PIN_0, 0xFF);

    return(0);
}