Publication of Android App Failed using Xamarin Studio

I'm using Mac with Xamarin Studio version 5.9.5 to Archive for Publishing my Android App.
I followed the steps in "Part 1 - Preparing an Application for Release" to publish the app but I encountered error at the end of publishing. It saying "Publication of the app failed. You need to manually upload your APK to Google Play". I tried to manually upload to the Google Play but it failed due to the APK is not zipalign.
Based on the Xamarin online doc, with this version of Xamarin Studio, it will automate the uploading process.