THEMA: Can not create a new YouTube Video View. Please help

Hello.
Can not create a new YouTube Video View.
The following message comes:
We can not find this channel: https://www.youtube.com/channel/. Please make sure to enter only the parameter behind / channel /
Example: https://www.youtube.com/channel/mychannel
Click on the channel name under the video to find a channel url.

Tried everything. It does not work.
youtube.com/watch?v=XXXXXX
Had before the new feature subscribers! no problem.
Many Thanks.

Please try again - this problem should be solved.