Error in outlook add-in when user assignment is Proposed

If you have an assignamet which has got its booking type as Proposed you will find that outlook add in gives you a message like this "You have not any assignments to upload" when you try to import new assignments. This hapens becouse resource hours are not reserved, as the user is just proposed for the project.
To solve this change user's booking type from Proposed to Commited. This can be done editing the resource from the resources pages.