a little update
i tried to set the theme manually at certain controls such as the ribbonbar and that actually works
i then noticed that i could add the theme to the ribbonbar and even a Border but when adding it to a RadOutlookBar the designer throws an exception and i also get the same exception as before during runtime
if i set the theme to a RadDocking control that ultimately contains the RadOutlookBar the design view still works but the outlook bar disappears. Then when refreshing the design view the following error occurs
well i checked and noticed that my reference to the theme was pointing to an older version of the telerik dll not the 2011 Q1
changed the reference, rebuilt and all is happy now ...