Hi Imran,
You might have restricted all the cells with the same restriction for month/year. Check my earlier reply. You have to add the restriction for each cell individually. May be use a offset value for each cell( Jan, Feb = +1, Mar = +2...Dec = +11).
BTW, there are some many replies to this thread and people are putting their efforts to help you. Please mark those that you found helpful using the 'Mark as Helpful' button.
Benedict