android - Scanner return null -

im using 3rd party library (zxing) bar code scanner . result of scannig null. after scann try adding result label result null.

here code :

if (requestcode === scanner_request_code && resultcode === android.app.activity.result_ok) {                      // handle successful scan                      var contents = intent.getstringextra("scan_result");                      var format = intent.getstringextra("scan_result_format");                      // var scanned = page.getviewbyid("scanned");                     //scanned.url = "";                     pagedata.set("message", contents);                     page.bindingcontext = pagedata;                     }