The error message that you are getting means that a transition has no source status. A transition is the section in between two statuses. Each transition will need to start from a status and end on a status.
I would suggestion you look through your process to make sure there are no holes anywhere and that the lines are all intact.
I thought that as well, but the process works fine before the three decision blocks at the top of the tree. I'm wondering if its a bug, not possible, or any alternatives.
I don't see any problem with your process. If you just add in the one decision at a time, does it error then too?
I have just had something very very similar and I found it was because of the pre-condition after the 'Open' status. I figured that process designer was evaluating the process and resulting it been that a ticket could be opened and go straight to an 'Other' status rather than firstly entering a start status for example, 'Open'.