Your code will not compile. you can do as below
SqlDataReader rdr = SQLcmd.ExecuteReader();
while (rdr.Read())
{
lblCreatedDate.text = rdr[0].ToString();
}
since you only need one column value you better change the sql statement something like below
SELECT TOP 1 column_name FROM table_name
ORDER BY column_name DESC;
then you will get one row as the result.