Android library projects cannot be launched

[I0riYagami]

Hi guys,

I am trying to create a QR Code scanner mobile web app using phonegap framework.

I have follow the below websites tutorial and there are good tutorials but I encounter a problem.

http://mayukhsaha.wordpress.com/2013/07/09/barcode-qr-code-scanner-and-encoder-using-phonegap-android-and-eclipse/comment-page-1/#comment-203
http://simonmacdonald.blogspot.sg/2011/12/installing-barcode-plugin-for-phonegap.html

I am suppose to do the following which is part of the steps. "In the Properties dialog, select the Android tab and ensure the Is Library checkbox is click."

But if I check the 'is library' checkbox, I will not be able to run my app as it will display an error at eclipse "Android library projects cannot be launched"

If it is unchecked, my app is able to run and I am able to see the below interface on my phone but the QR code scanning and encoding function will not work.

Using:
Eclipse
ADT
Phonegap Cordova 2.9.0
Barcode scanner plugin 2.2.0

please assist. Thanks