Dynamics CRM Integration with Yammer

I have not used Yammer much. Have recently integrated yammer with CRM. I want to know, can we not post anything at all without tagging a group and just tag a user? 

When I try and do that, it says please tag atleast one group.

So, Iam able to either post without tagging anyone at all. Or, if i try and tag a user, it doesn't let me post unless i ALSO tag a group.