set bar code to string builder

Question

   i am generating bar code using zen.barcode

like this 

Zen.Barcode.CodeQrBarcodeDraw brcode = Zen.Barcode.BarcodeDrawFactory.CodeQr;

and now i want to set this barcode to string builder table column.

sb.Append("<table>")

sb.Append("<tr>")

 sb.Append("<td> brcode.Draw("read 200000 faliure " + (ab * 1.5).ToString(), 16)")

but it is not display in pdf document.why?