500 when trying to an account to billing Admin section

When trying to add an account to the billing section: http://qa-vumi.za.prk-host.net/admin/billing/account/add/

Once I have entered all the info and clicked 'save' I get a 500

![screen shot 2013-11-18 at 11 38 41 am](https://f.cloud.github.com/assets/1521387/1561807/45849594-503b-11e3-8ef0-769d7fcec742.png)