Let me explain this issue with the webshop : - we had a custom developed web shop before. In this old system, the state/province field didn't exist. - we switched to a new platform to be able to support for more option. This switch was done for the panobook last december. In this platform, the state/province field is needed but the import routine could not fill this needed field. So if you want to place an order and if you didn't correct this part in your account, address, you cannot as this field is mandatory. To correct that, just go to "my account", edit the address and validate it once at least. It will check everything and the basket process will then work.
It's a bit long as an explanation, but illustrate some issue that can exist behind the scene