The problem with objavlenie war. (Stellaris)

May someone tell me.
The problem is that I can't declare war on another Empire.
The situation is this: There is a colossus, it is possible to start a war of annihilation, but(!) a war of extermination can only be started with rivals. And I'm at the stage where even all extinct Empire for me the worst. And to make Empire option is Worse his rival is not.
On entering claims, and then fail. Click on claims and show that With the Colossus we do not need to declare a claim.
It happened once that destroying the Outpost I was able to distribute brittaneyane for the whole Empire as she stopped granichet with me, but there was only one Hyper the corridor. But if the situation is such that the floor of my Empire borders another, nothing to do.