Hi Cyril!
VI Pro offers the possibilty to enable and disable patches and matrices. Disabled patches are displayed in light blue. They are not loaded to the RAM and cannot be played. This is not a bug, but a feature. [;)]
If you want to use the Special Edition Volumes 1 and 2 and the SE PLUS Volumes 1 and 2 with Sibelius, use the Special Edition PLUS sound set and load the Special Edition PLUS matrices (= the ones with the "+" at the end of the name; not the VI Pro matrices).
You can learn all details in the "VSL and Sibelius 7" tutorial video and in the "Optimizing Sibelius Playback" manual at the following locations:
http://www.vsl.co.at/en/211/1343/1348/2459/2116.vsl
http://www.vsl.co.at/en/68/141/460/576/655.htm
Best,
Andi
Vienna Symphonic Library