error converting date time

Hi i m tring to convert a date time

declare @.a datetime
declare @.b varchar(10)
set @.b='26/04/2004'
set @.a= Convert(datetime, @.b)

but it gives me this error:

Server: Msg 242, Level 16, State 3, Line 5
The conversion of a char data type to a datetime data type resulted in an out-of-range datetime value.

I believe is my date format..i want to know how to make sure that i am the dd/mm/yyyy format is correct way?Why are you sending the date in as a varchar ?|||Use SET DATEFORMAT

Sets the order of the dateparts (month/day/year) for entering datetime or smalldatetime data.|||Hi,
thanks for all ur reply.. basically i wanted to send date in as dateTime but i cant because i cant assign a date to null so i have to send it to my database and from there i convert it to valid date time.

Thanks alot.