APK Signed In Debug Mode?

Hi all

I am trying to get my app ready for release, I have followed the steps outlined here:

http://docs.xamarin.com/Android/Guides/Deployment,_Testing,_and_Metrics/publishing_an_application/Part_1_-_Preparing_an_Application_for_Release

But when I try and upload the aligned APK to the playstore I get the following error:

"You uploaded an APK that was signed in debug mode. You need to sign your APK in release mode"

But I am definitely doing everything in release mode? I have done it twice now with the same result? What am I missing here?