Re: Message in Eventin: close is not a valid action for change
First check that the operator record used to process the eventin records has the close capability for the module you are using.
Check the profile the operator is using.
If you can't resolve like this, check the display option to see what conditions must be met to close. Either modify your operator to meet those conditions or create a second displayoption to give just your background operator access to close the ticket.