Try:
... WHERE rnd.Product_Id = @Product_Id and rnh.Receipt_Date between @DT1 AND @DT2";
using (SqlDataAdapter dr3 = new SqlDataAdapter(sqlstr3, CS))
{
dr3.SelectCommand.Parameters.AddWithValue("@Product_Id", txtProductId.Text );
dr3.SelectCommand.Parameters.AddWithValue("@DT1", @dateTimePicker1.Value);
dr3.SelectCommand.Parameters.AddWithValue("@DT2", @dateTimePicker1.Value);