I am clicking the button on the Blue Sky vending machine and get the message 'you cant buy that' and telling me to return there. I cant see that I am doing anything wrong, just using some Wizard tokens to buy books/items. Is there a glitch here and if so, can it be repaired quickly? Thank you.

Do you have tokens in your bank currencies?

If not you might need to have them in the inventory, click on them, and deposit them into your bank first :) (The system of how tokens worked changed a few weeks back to reduce the number of items in our inventories :)