If you are getting the following error message when your try to register for events
Salesforce Error: sbxe1.sbx_EventsCampaignMember: execution of AfterInsert caused by: System.DmlException: ConvertLead failed. First exception on row 0; first error: INVALID_STATUS, invalid convertedStatus: Closed - Converted:  (sbxe1)
The issue is that in Salesforce in the Leads under Setup --> Customize --> Leads --> Lead Processes, if you go to the Soapbox Events Registrations you may need to add some values to the Available Values area. If no values are in the selected values list there then the leads will not be converted when they come in and there will be no values for the leads to be processed with.