Error message when adding theatre ticket to wallet

When I try to add a theatre ticket to my wallet on my iPhone 13 I get a strange error message. I am clicking on the "Add to Apple Wallet" button contained in the vendor's email.

My wife's iPhone 13 adds her theatre ticket successfully. I've added flight tickets to my wallet before.

Does anyone know why this might be happening ? Here's the error.....

Thanks in anticipation,

Martin