I'll go out on a limb and suggest that the only person that could help (should he choose to) is the developer of QuickLaunch (CheetahAce I believe that would be). It's probably something that needs to be tweeked in the QuickLaunch code (much like it was for Media and Shazam).
What you are saying is that BBM version 5 (beta) does not work when called from QuickLaunch. This is so, I wrote to the people behind QuickLaunch development, and the replied that this a known issue with version 5 of BBM. They are hoping to solve this in their next release.
There is another thread (at least one!) that talks about this problem.
Meanwhile you can always access BBM from the menu system of your BB device.
just curious as to why you really need bbm in quicklaunch anyway, not that you aren't entitled to it if you want it, but it's always running, so why not just hold the menu key down or alt+back to get to app switcher and access it from there? it's quicker anyway, less clicks to get to it
yeah, maybe i'm just a minimalist when it comes to my BB, but i can't even wrap my mind around when you'd even want a quicklaunch link for bbm, personally i have mine linked to the right convenience key, but, theres already a homescreen keyboard shortcut to it, and its always running anyway.... i only use quicklaunch menu items for shortcuts for items that i can't access via a key or app switcher
bump 
