What is this symbol?

Hi Guys, so this is probably something really stupid. But as I am using VSL Ensemble now the Audio Inputs of the Plugin show this symbol. It turns out VSL Ensemble only works propperly when this symbol highlights in blue. I can’t really look it up in the manual since I dont know any term to look for. Hovering over it does also not give my any info.
Screenshot 2016-07-03 10.26.26.png
So the question is:What is this symbol? And how do I make it turn blue?

Also while I am on it, what is the other symbol there looking a little like this?: --

Sorry, I know perfectly how this question sounds :wink:

Thanks for your answer in advance

The symbol indicates that a send is active, the other one indicates that an insert is active.

… and the button will only turn blue if there is actually a Send on the channel (the button itself is for Bypassing the Send… turns yellow when bypassed).
But I’ve no idea why you would need a Send on the channel in order to make VSL work :confused: