I have checked all this four files,There is nothing about couatl and addon manager
That's not what I've asked to do. It's normal you won't have the Addon Manager there, because that's how it's supposed to be. The Addon Manager is installed in its own add-on.xml file.
What I asked to do, instead, was to check if ALL your XML files are syntactically correct because, there might be a problem of loading other modules if one of them has an error.
That's why I suggested to
open them with Internet Explorer, and see if there's any error reported. ALL 4 of them.