Streaming with YT on obs not possible because of stream key supposedly wrong?

So, when I start to stream, I immediately get the error message that the stream key is wrong (I also stream times with xsplit, but with fortnite etc. Is that too slow) Now I've made all the settings again and the key again It's still not done, who does not know what I could do?

So reinstall OBS?

Villeicht internet check? Could be yes that it does not work.

There's no more possibility anyway:-(

Wish you luck!