I know this thread is a few months old but Im having the exact same problem with r99.
<img src="https://dl.dropbox.com/u/53012532/BarcodeScanEvent.png" border="0" />
thats the exact event sheet thats all the program does. I export as appmobi without direct canvas and install on my 2.3.4 android phone run the app and click the button the scanner opens I scan a barcode and its like the app just restarts it flashes for a sec and then the text is never changed from the default value