Hey there Janmacky67,
I'm sorry to hear that the Chromecast is giving you some trouble! Sometimes, it can be tricky to get the device working the way you'd like it to, so I'd be happy to help. First, I would check out this guide on how to cast. Go ahead and follow the steps listed, and if you have any issues or error, let me know what is occurring.
I look forward to your response, and if you have any other questions or concerns for me, please let me know!