Tom Atkins

Thanks for the info in this thread folks - it works!

Couple of things to be aware of:

1. Make sure the 'type' of the organization field and ticket field is the same (e.g. both 'decimal')
2. The HTTP target must be 'PUT' method to update a ticket
3. You can use 'basic auth' credentials in your HTTP Target settings with an API token - the 'Username' field should be an email address for a full agent account in the form: YOUR_EMAIL/token (note the '/token' after the email address) and the Password field will be a Zendesk API token that you have created.