I'm using a Macbook Pro 15"; OSX 10.6.4, Sibelius 6.2, & VDL 2.5.2 with the 6.0a template.

I've had issues before with the Bassline unisons not sounding, & everything else playing back as normal...

As I was working on a project last night, (which previously everything was sounding just right) it all of a sudden had no more playback.  I know that I didn't tweak anything within Kontakt Player, or VDL, just re-opened the project.

Any ideas?

A couple things to check which might help narrow down your troubleshooting:

1) Restart the machine if you haven't already.

2) Is it just Sibelius that has no sound, or do other apps go silent as well?

3) If it's just Sibelius, go into your Audio Engine Options window (via Playback Devices) and see if something may be going on in there.

4) Try loading a different playback configuration (i.e., Essentials) and then playback. Your sounds probably won't be all correct, but this may give you some audio. Then switch back to your other playback configuration and see if you achieve different results.

I restarted the machine, re-opened Sibelius.  Played the file as-was, still no battery sounds.  I do get front ensemble sounds, however, they aren't what they were supposed to be.  There are also winds sounds as well.

I loaded the ";Sibelius Sounds"; playback config, & the battery played back, with the exception of the silent bass drum unisons I've had.  I then reloaded the playback config cleverly named ";Nick,"; which included the Kontakt Player 2, & VDL Template 6.0a, & I still have no battery sounds.

Should I try to create a new playback config?  I've done this before under Bryan Harmsen's advice, & it seemed to resolve the problem I had at the time.  But that is how I got my new configuration named ";Nick.";

It's also possible that depending on how many instances of Kontakt Player 2 you have activated, you've possibly run out of available channels for the battery stuff to load. There's a setting in Sibelius 6 that will warn you when this is the case, but it's possible you may not have it activated.

Before you create a new playback configuration, try activating another instance of KP2 into you ";Nick"; configuration, and assign the VDL SoundSet 6.0a to it. Save the configuration, then try playing again and see if your battery sounds reappear.

If that doesn't help, it might not be a bad idea to just create a new playback configuration from scratch with a couple instances of KP2. You can even call it ";Nick  2"; or something cool like that! :)

Hang in there. I'm sure there's a fix right around the corner.