When ever i try to buy global for $4.99 it gives an error
Also what version of IF do you have? The current global costs $10 not $5 like before global. This issue usually comes up when trying to buy when not updated to global.
Which version of Infinite Flight are you using? This usually happens when you try to buy a subscription on the older version of Infinite Flight (pre-global).
Version 16.03 is pre-global, which means that in-app-purchases are no longer supported. You will need to upgrade to a device that supports the global update in order to buy a subscription.
If you have any questions regarding a specific phone/tablet, feel free to PM me.