Date format not valid

Hello,

Sir i would like you to help me on the following problem, i am filling an application form and i have done everything but on the date side the system is refusing me from sumitting the form. It is saying the value is not valid, but the form am to submit before tommorow so please Sir send the email now i was born on 25th december 1996. (dd/mm/yyyy) and i have been writting like this (25/12/1996) but still it says no. please sir give me the answer now