Test Case Designer - Connectors before first function

Hi, 

I am having a model in which and event triggers the first function, but also this function is triggered by some end events from the process itself. Please see picture for details (it is ARIS Express, but I am having the model of course in ARIS for SAP). 

When I try to start the test case designer: there is no start point selected. If I insert a start event and a helping function before the 'old' start event, everything is working fine. Is this only for Test Case Designer so, or I am understand the modeling rules wrong? 

Thanks 

Jessica