Remove duplicated row from datagridview c# -

i want unique rows. loop should check rows in datagridview , see if matches text textbox, if not, add value textbox datagridview. problem: first row works, loop iterate through first row in datagridview, why wont continue through other rows?

private void laggtill_click(object sender, eventargs e)         {              bool dublett = false;                        foreach (datagridviewrow r in datagridview1.rows)             {                                               if(r.cells[0].value.tostring() == txtnamn.text)  // txtnamn textbox                 {                     dublett = true;                     messagebox.show("varan finns redan, gör om!");                                     }                 break;             }             if(dublett == false)             {                 datarow dr;                 dr = dt.newrow();                 dr["namn"] = txtnamn.text;                 dr["pris"] = txtpris.text;                 dr["varunummer"] = txtvnr.text;                 dr["saldo"] = txtsaldo.text;                 dt.rows.add(dr);                 datagridview1.datasource = dt.defaultview;                 clearrow();                 spara();                             }             txtnamn.text = "";             txtpris.text = "";             txtsaldo.text = "";             txtvnr.text = "";                     } 

if(r.cells[0].value.tostring() == txtnamn.text)  // txtnamn textbox {     dublett = true;     messagebox.show("varan finns redan, gör om!");         break;                 } 

move break; inside if.