Shopify POS doesn't detect card reader in a different country

[theheadplan]

I'm based in Ireland. I set up a Shopify Store with an Irish address but using GBP as the currency. I'm attending a sales event in the UK and brought my iPad with Shopify POS and WisePad 3 Card Reader along. 

The problem is that it can't find the card reader. 

Can someone help explain why this is?

Am I correct in saying that legally the store address needs to be in the UK too ?