Shop won't allow me to upgrade from 149 to 199 island expansion

I purchased the 149x149 expansion a few days ago for Economy and decided I would like to get the upgrade to 199x199 today, however the shop is telling me "You're not allowed to purchase this item" when I try to add it to the cart. I've made sure I was logged into the shop with the correct player name and the right server, however can't seem to get it to work. Screenshot below.

I'd like to buy this while the sale is still on, so any help is appreciated!

Thx!