Linear model with 2 Material properties

Hello All,

I am trying to model a bracket made of Aluminum which has Steels bolts. I am not modeling a contact phenomenon. My steps are as follows:

1. I created two boxes one on top of another 200mm cubes.
2. I made a compound using these two called BrktAll.
3. I grouped the top face as "Force" and the bottom face called "Fixed"
4. Then I exploded them into two Solids, the upper one called "Bolts" and the lower one called "Brkt"
5. I created a Group called "Bolts" and one called Brkt" each containing the respective solid "Bolt" and "Brkt"

6. Then I meshed "BrktAll" with Quad Tetrahedral elements using Netgen-1D-2D-3D rules
7. Next I grouped all nodes of geometric group "Fixed" as node group "Fixed"
8. Same with all nodes of geometric group "Force" as node group "Force"
9. For the material properties: I grouped all volume elements of geometric group "Brkt" as "Brkt" and
all volume elements of geometric group "Bolts" as "Bolts"
10. Exported the mesh to a MED file and ran Code-Aster.

I get the following:

!

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!
! <A> <MODELISA4_8> !
! !
! !
! -> Phase de vérification du maillage : présence de mailles doubles (ou triples, ...) !
! Les mailles multiples sont des mailles de noms différents qui ont la meme connectivité !
! (elles s'appuient sur les memes noeuds). !
! !
! -> Risque & Conseil : !
! Le risque est de modéliser 2 fois (ou plus) l'espace. On peut par exemple avoir !
! un modèle 2 fois trop lourd ou 2 fois trop rigide. !
! Remarque : les mailles concernées sont imprimées dans le fichier "message". !
! Sur ce maillage, il est imprudent d'affecter des quantités avec le mot clé TOUT='OUI'. !
! !
! !
! !
! Ceci est une alarme. Si vous ne comprenez pas le sens de cette !
! alarme, vous pouvez obtenir des résultats inattendus ! !
!

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!

Can somebody guide, correct or suggest the commands I should use to overcome this problem please? My comm file is attached.

Here are the files:

Here is the image file to conform to 600 pixel limit!