I am using Magento 1.9 and have installed the Wallee extension from github.
I have configured Wallee and Magento with the application user id and key, also the website space Id.
I have setup a processor (SagePay) and a payment method (secure credit / debit card) and 4 connectors (mastercard, visa, amex, maestro).
Using the standard Magento OnePage checkout.
Transactions are being rejected by SagePay as they include a BillingState that is greater than 2 letters. I have spoken to SagePay support and the say this is only needed if it's a US address.
The UK address I have been using is giving a HEF BillingState as it is in Herefordshire.
It works fine with a Cambridgeshire address.
Sagepay say there is no need to send a BillingState with a UK address, but if it is sent it needs to be 2 letters.