Tables :: Default Value Equal To Date Entered By User

I want a default value to equal the first 2 characters of field [first name] and first 3 characters of field [last name] and the numeric datevalue of [DOB] 'date of birth'.

In excel its easy,
C D E resultformula
AndrewTester12/12/1980AnTes-29567

Formula LEFT(c9,2)&LEFT(d9,3)&"-"&e9

How do I get same result in Access?

tried

Field 'PRN', a text field set as default =""""& left([first name],2}+LEFT(Last name],3), date()&""""

Access accepted the above statement but when I input user details the default doesn't work.