InApp Purchasing

Like some others, I am experiencing InApp purchases, in this case the game ‘Boom Beach’.

In the App Store, I am able to download free purchases and apps which cost money. Those payments go through no problem.

Payments to stores like Amazon, Tesco are no problem.

Why have I got a problem with In App purchases for that game?

I think I’ve done all the standard stuff for the iPhone. It is a new phone but it is synced with the old one & the bank details are correct.