Fernando... Please, have your time to release next update... I'm checking
http://ozviz.wasp.uwa.edu.au/~pbourke/dataformats/directx/ (DX file format), and it seems that I already find where's the corruption... I must have messed when I inverted the "Cabeca" bone so, Blender losts reference about its frame... Thanks!!
EDIT - I rebuilt the armature, set the idle animation to only one frame, and then there seems to write the frames I need... Maybe if I actually do some animation (i.e., increase the number of frames) could it work...

Late... Will do some experiments on it later... Thanks!!
EDIT2 - Here's the updated model... Please, Fernando... Meanwhile, could you check if now the file is corrupted or I just need to "animate" it? (please, note the model goes from frame 1 to 1 with a keyframe inserted on this frame so, it just reverts back to the position a human normally stands...

, 3DRad actually recognizes this keyframe)... But still, there is nothing to animate... And still, the animation controls are still disabled...

Very late for work... Thanks!!
EDIT3 - Now, it's recognizing... I did some bone parenting (check attached file)... However, the armature world transformation isn't corresponding to the model one, which is causing the model to be rotated -90 degrees along the X axis... Please, do you have any clues about what can I do now? Thanks!!