planned order

Hi All,

This is a very basic question i am sure to get an answer.

when i create a planned order in product view before a particular date (say 11th august) it changes availability date to 11th aug. that is irrespective of the date i am putting in (1,2,3...upto 11th august).

but when i try to do same after 11th, it gives me same date which i supply...example if i want planned order to be available on 11,12,13....etc it will give 11,12,13....etc.

what all can be the reason behind this particular behavior?