On a Fresh FA v2.3 setup, I'm trying to process a payment to a supplier but nothing happens when I click on 'enter payment'.

I can go through all of these without a problem:
Purchase Order Entry > Outstanding Purchase Orders Maintenance > Supplier Invoices

I probably have missed an important config setting somewhere. I don't know much about accounting. I have setup the compagny details / taxes and taxes groups / bank accounts / GL accounts and suppliers.
Have I missed something?