Default [Q] i am unable to take backup of my mobile

i am unable to take backup of my mobile
Phone-lava iris 455
Ram-512mb
when i enter into the power mode by pressing Power V up key then i saw the three option there
1. factory reset
2. update from SD card and
3. there is a option for backup and restore
when i used 3rd option it says unable to take backup or any other error . . .
then what is the use of 3rd option there
someone please tell me