Just touch Android, not very familiar. After discovering that items that can be packaged properly before adding confusion and then packaging the signature apk, you are prompted with "Android Proguard failed to export application".
Comment out the proguard.config=proguard.cfg in the program (in the Project.Properties file), and then package the discovery without confusion to properly package.
Finally found the reason, originally upgraded the SDK to 20.3 version today, the SDK installation directory is missing a confusing directory Sdk\tools\proguard missing the relevant tool files, download the corresponding version, here i download is 5.0: Click here to download
Then unzip the relevant files to Sdk\tools\proguard (note: The name must be Proguard, otherwise it will not succeed), this is re-open Eclipse project to be confused repackaging, should be.
Inspiration from: http://blog.sina.com.cn/s/blog_6e334dc70102uw33.html (the above method is not successful can see here)
Android Proguard Obfuscation Signature package appears "Android Proguard failed to export application" solution