This problem occurs just with the Jackal model, with all the other bipeds/tags everything is OK. I made a custom animation for the Jackal, and everything is right: the model is linked to the Pelvis node, there aren't unrigged vertices, each node is in the right place. I didn't touch anything. But when I try to export the animation, it says that there are too many actors to export. I checked everything, and it seems the both the Pelvis node and the Spine1 node act like root nodes, even if the Spine1 node is linked to the Spine node or the Pelvis node (I know that it shouldn't be linked to the Pelvis node, it was just a test). I broke all the links and relinked everything in the right order. Same result. I even tried to export a stock animation with the stock Jackal model, and I always get this error. Other models, on the other hand, work perfectly. My conclusion is that there is something wrong with the stock Jackal boneset. Has anyone else had this problem too?

You don't even need the model to export animation, let alone rigging. I'd say to delete it so it doesn't cause any problems. You only need the bones, with the pelvis bone as the root. Do you have a screenshot of your bone hierarchy?
Edited by Koo294 on Sep 19, 2013 at 02:55 PM

If I remember correctly the jackals had a extra "type" of node for there shield I believe a frame node. That's your problem not your Spine1 node. Your exporter see's frame nodes and bip01 nodes as two different types so as long as there "named" << Hint Hint
this way It will always say to many actors in the scene.

I renamed the "frame" nodes with "bip01", and it worked. Thanks a lot, DarkLord!