SD card

hello dear all,
I have a problem in create a text file in SD card. here is my code. it doesn't create text file. i work on LPC1768. would you tell me what is the problem with my code?

FATFS fs;         /* Work area (file system object) for logical drive */
FIL fsrc;         /* file objects */
FRESULT res;
UINT br;
int SD_TotalSize(void);
char path[512]="0:";
uint8_t textFileBuffer[] = "Thank \r\n";
FRESULT scan_files (char* path);

f_mount(0,&fs);

 res = f_open( &fsrc , "0:/Demo.TXT" , FA_CREATE_NEW | FA_WRITE);

    if ( res == FR_OK )
    {
      /* Write buffer to file */
      res = f_write(&fsrc, textFileBuffer, sizeof(textFileBuffer), &br);

          printf("Demo.TXT successfully created");

      /*close file */
      f_close(&fsrc);
    }
    else if ( res == FR_EXIST )
    {
          printf("Demo.TXT created in the disk");
    }

        scan_files(path);
        SD_TotalSize();

    /* Infinite loop */
    while (1)
                {}
}