Recovery of Unrealised Rent

Dear All,

I am having one problem:-

if u r having any unrelised any rent during the P.Y.then u will not take this for calculation of Income from House Property and 30% deduction u/s 24 would not be available to the assessee.

and while r u receiving unrealised amount during any coming P.Y.,whole amount would be taxable under the head Income from House Property.and no deduction is  available U/s 24.

Q. is why we are not giving 30% Deduction U/S 24 during receiving the amount?