Hello everybody, I got a big problem with my tank model
I think these two pictures should show you my problem.
Well the problem is that the turret of the tank is at the wrong position.
Any ideas? It would be nice if anyone could help me.
Ps: Thx in advance

Just looking (from the bits of the XSI tree I can see) I am going to take a wild guess that you did not included the body of the tank in the enveloping process. I can almost tell that the tree starting at gun is a child of the main body. It is also had to see all the nulls but you didn't freeze transforms on any did you?

Is the tank all one model mesh (or is it separate bits) because all the nulls are blue I am guessing you enveloped each bit separately to it's respective null, while not wrong it can cause problems (or it has for me) Anyway I'll stop making this long story longer and say

If you merge all the bits together (don't forget to merge UV materials etc) then press the delete inputs, button at the top, then include a bone_root null and place the gun tree underneath it. Select the newly merged mesh, do set envelope and select all your aimer nulls as well as the bone_root the adjust the weights so all the bits you do not want to move are weighted to bone_root and all the other moving parts are weighted to their appropriate nulls.

Hope that helps, also another tip for displaying more of the tree for picture taking purposes, see where it says All Except Parameters, click on that and select Objects Only it will show only the nulls and mesh bits in the tree. You can always set it back afterwards.

Thx for the fast help fragme!, everything is working now.
Now I have a problem with the minigun on the tank, but I'm going to fix it.