My b2evolution Version: 1.10.x

I just installed b2evo through hostmonster and it seems that something is wrong.
Some tasks I want to perform like install plugins, install new skin, etc., instead of directing to http://mydomain.com//admin.php/?ctrl=skin&action=new it does not consider my domain name and tries to connect to http://admin.php/?ctrl=skin&action=new and of course I get the server not found error.

It does direct correctly from the dashboard to the Administrative tasks levels.
But once I am inside the Adminstrative Task Level (it directs wrongly, no conisdering my domain name and jumping directlyu to http://admin.php/... etc.
:-/ :-/ :-/ :?: :?: :?: