c# - ZXing.Net ITF Barcode issues Windows Phone 8.1 -

i can decode barcodes itf using zxing.net, in cases result.text have missing numbers, in this:

original barcode: 836900000008262500403007233338786038100661049195

result.text       : 83690000000  26250040300  23333878603  10066104919

in case there missing 8,7,8 , 5

in other case, numbers reordered random order , have missing numbers:

original barcode: 23793381285017475716618000050809162310000010000

result.text         23791623100000100003381250174757161800005080

ideas why happening?

thanks

edit: 06/12/2015

if don't specify possibleformats decoder decodes codes (the images here:1drv.ms/1b6wd5c) itf , result same described above. code i'm using here:

    public barcodereaderservice(idialogservice _dialogservice)     {         dialogservice = _dialogservice;          barcodereader = new barcodereader         {             options = new decodingoptions             {                 purebarcode = true,                 tryharder = true,                 possibleformats = new barcodeformat[] { barcodeformat.itf }             },          };     }      public async task<string> scanbitmapasync(storagefile file)     {         string result = null;         using (var stream = await file.openreadasync())         {             // initialize 1,1 current size of image             var writeablebmp = new writeablebitmap(1, 1);             writeablebmp.setsource(stream);             // , create again because otherwise wb isn't initialized , decoding             // results in indexoutofrange             writeablebmp = new writeablebitmap(writeablebmp.pixelwidth, writeablebmp.pixelheight);             stream.seek(0);             writeablebmp.setsource(stream);               try             {                 result = scanbitmap(writeablebmp);             }             catch (exception ex)             {                 dialogservice.showasync("ocorreu um erro \n" + ex.message, "erro");             }         }          return result != null ? result : null;     }      private string scanbitmap(writeablebitmap writeablebmp)     {          var result = barcodereader.decode(writeablebmp);          return result != null ? result.text : null;     } 

the missing numbers indeed validation numbers , have calculated.