Hello dmagiardi!
Vienna Ensemble is the host for Vienna Instruments. Maybe you have noticed, that the instruments you have inside Vienna Ensemble are exactly the same as the Vienna Instruments.
For a general introduction on working with Sibelius and Vienna Ensemble I recommend the Sibelius 5.2 and Vienna Ensemble Setup guide you find at the following location:
http://vsl.co.at/en/68/375/377/239.htm
Our tutorial video might also be of help. You can find it here:
http://vsl.co.at/en/211/1343/1348/243.vsl
When you assign a sound set, please don't forget to make channel and program settings on the Manual Sound Sets page afterwards. Maybe that was the problem.
Andi
Vienna Symphonic Library