pass time and date to stored procedure

Question

private void in_Time_Click(object sender, EventArgs e)

        {

            sqlCon_fn();

            sqlcmd = new SqlCommand("Emp_att_out");

            sqlcmd.Connection = sqlCon;

            sqlCon.Open();

            DateTime T = DateTime.Now;

            sqlcmd.Parameters.AddWithValue("@out_time", SqlDbType.DateTime);

            sqlcmd.ExecuteNonQuery();

            sqlCon.Close();

        }

i want to pass the time to strored procedure(Emp_att_out) ....This is my code ..bt i got error    Procedure or function 'Emp_att_out' expects parameter '@out_time', which was not supplied.