I have followed your tutorial for making a score using Vienna Standard Edition Plus xml file and it works.
I then have copied the Solo string I & II xml file but it didn't work.
The playback device only finds Solo string I & II in the configuration, and the playback device only finds VSL Ensemble Special Edition Plus in the Sound set
Windows Vista 64 and Sibelius 6.01 ( I only have VSL Solo strings I and not the II collection)