Filter datatable c#

Question

Filter datatable from text box and datetime picker

 

private void izvjestajoprodanimartiklima()
       {
           using (SqlConnection openCon = new SqlConnection(cs))

           {

               String saveStaff = "SELECT  roba as 'Naziv artikla', SUM (cast(kolicina as float)) as 'Kolicina' from (select roba, kolicina from mp_racun_roba union all select roba, kolicina from mp_faktura_roba) as alltables group by roba";




               if (!string.IsNullOrEmpty(textBox1.Text))
               {
                   saveStaff += "roba LIKE '%" + textBox1.Text + "%' ";
               }


               if (checkBox1.Checked)
               {
                   String strFilterDTP1 = dateTimePicker1.Value.ToString("yyyy-MM-dd");
                   String strFilterDTP2 = dateTimePicker2.Value.ToString("yyyy-MM-dd");



                   saveStaff += strFilterDTP1 + " 00:00:00' AND '" + strFilterDTP2 + " 23:59:59' ";

               }

 error   line 14   Incorrect syntax near the keyword 'LIKE'.

 

Some help?