Scenario Unplayable (spoiler Alert!)

Hi, I noticed that the Scenario "Ich bin kein Mechaniker" (I dunno how it is titled in English) is unplayable. It says that I should drive a train to Traunstein and till now it's all good. As soon as it says that I should change the locomotive because the one I drove broke down, you shift to a platform backwards and afterthat you should shift to the main route to Freilassing. But I noticed that I can't because the signal stayed at red although there's no other train except the broken one but I am 100% sure it's not the one who's blocking my way. And there wasn't any other train on the way which could block my way to the designated marker. And yes, I also contacted the dispatcher and he said that there was apparently another train in front of me, although there was no other train except the broken one that was on the platform in Traunstein. Maybe I had to wait longer and if that's a mistake on my part and I just had to wait longer, then I apologise for my clumsiness.