problem with File system middleware

hi,
i am working on a project that in it i need to write and read sectors in sd card, i decide to use keil File system lib with mci driver but i have problem to write sector in sd card but reading is ok. i use below code to initilize sd card:

if (finit ("M0:") != fsOK) {    // Initialize File System
    return 0;                             // Exit if failed
  }

  id = fs_ioc_get_id ("M0:"); // Get ID of media drive
  if (sdcard_drv_id < 0U)          { return 0; } // If ID is invalid exit

  status = 0U;
  if (fs_ioc_device_ctrl (id, fsDevCtrlCodeControlMedia, &status) != fsOK) {
    return 0;                             // Exit if failed
  }



  if (fs_ioc_lock (id)) {           // Lock media for USB usage
    return 0;                             // Exit if failed
  }
  st = fs_ioc_write_sector(id,0,buf,1);
  if(st != fsOK)
        return 0;

when i call fs_ioc_write_sector in above code it returns FsError(0x01) but when reading sector it work correctly.
can any one give me an advise to solve that??