These should help:http://bulletphysics.org/mediawiki-1.5. ... ser_manualhttp://bulletphysics.org/siggraph2011/m ... ph2011.pdf
It sounds like you are attempting to add a rigid body sim to an existing scene? this is possible, but you will probably have to setup the sim, clear out all the non-sim nodes, bake the sim, and re-import it into the existing scene. Rigid body sims are often the base on which other sims and effects are added - Dynamica assumes this workflow though it can be integrated into existing scenes.