I have followed all the steps in Installing and configuring workflow for SharePoint 2013:
http://technet.microsoft.com/en-us/library/jj658588.aspx
I have gone through all the validation steps of making sure all the services (service bus, workflow back end, etc.) are running, and the SharePoint service application says it is connected. I've checked the Microsoft-Workflow event viewer logs, and I don't have any errors.
However, after I connect to my SharePoint 2013 site with SharePoint Designer 2013, I get the following error when trying to create a 2013 workflow:
"The option for the SharePoint 2013 Workflow platform is not available because the workflow service is not configured on the server. Please contact your server administrator."
Any suggestions?