Sometimes the rigging in a BVH just isn't compatible with Poser figures. You can address some compatibility issues using BVHacker (http://davedub.co.uk/bvhacker/), which can help give you some idea of what's going on inside the BVH itself.

I guess the first questions to ask would be, where did you get the BVH file? When you import the BVH and it asks you about the orientation axis for the arms, what option are you selecting?

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Cage can be an opinionated jerk who posts without thinking.  He apologizes for this.  He's honestly not trying to be a turkeyhead.

Cage had some freebies, compatible with Poser 11 and below.  His Python scripts were saved at archive.org, along with the rest of the Morphography site, where they were hosted.