Internal Error In Activation System..

When I try to build the Hello Android project, I window opens that says "There was an internal error in the activation system. Please contact Xamarin Support with the following information.

System.NullReferenceException: Object reference not set to an instance of an object. at Xamarin.Components.Ide.Activation.ActivationDialog.ErrorBody..ctor(Exception error) at Xamarin.Components.Ide.Activation.ActivationDialog.DisplayWorkflowStep(ActivationWorkflowStep step) at Xamarin.Components.Ide.Activation.ActivationDialog.<>c__DisplayClass13.b__12(Task t)

I an using Xamarin Studio.

After closing the window, the following build errors are shown (both on line 291 of Xamarin.Android.Common.targets):

1. Could not determine $(TargetFrameworkVersion) for API level '19.' (XA0000)
2. Unable to determine license edition (XA9010)

This is my first time trying to use this IDE so I have no idea what is going on.. help!