Goto_location in Slash Command reponse

Hi,

Based on documentation, I wanted to implement this on a bot that I'm creating:

https://docs.mattermost.com/developer/slash-commands.html

Use the field goto_location with a URL as the value to redirect the user of the command to a webpage

I'm putting the URL but I get redirected to the Team Selection page. This happens in the client and also in the web interface. I'm using version 3.4.

I know the URL is correct, because I'm also posting it to the channel and clicking on it works.

Is the URL supposed to be in some special format here?

Any help will be appreciated.

Thanks

For those interested, I'm making an integration with http://appear.in and I want the person that initiates the call, to redirect them to their video chatroom.