create 3d model in .X file

Hi all

How can i make my own animated 3d model without external x eporter?
just make the model, animated the model and then save fair as X file.
I use blender for this, but if i import the x file to the project in C# (XNA) then i have the error with wrong index or something like that.

error look like this:

Error 1 Building content threw ArgumentOutOfRangeException: Index was out of range. Must be non-negative and less than the size of the collection.