Working With SqlCommand And Parameters

i am inserting into a table using the sqlCommand parameters property.for example i do :sqlCmd.Parameters.Add("@date_birth_hebrew", Request("date_birth_hebrew"))the date_birth_hebrew is not a must and has allow null value in the db.when the user submits the form and leaves the textbox of date_birth_hebrewnot field out and i try to add this value to parameters as the above code i recive :Prepared statement '(@date1 datetime,@first_name nvarchar(4000),@last_na' expects parameter @date_birth_hebrew, which was not supplied. as i understand beacuse the Request("date_birth_hebrew") is empty the sqlCommand.Parameters acts as no value entered.i hae solved this problem by on each value checking thatif Parameters Request("date_birth_hebrew")="" thensqlCmd.Parameters.Add("@date_birth_hebrew", "")but isnt there any another way?thnaks in advancepeleg