Please help with 3d model invisible in game.

I am new to modeling, and I wanted to do something easy. I modeled up a terrible version of a bus addon for the Gavril H series Van. Everything looks perfect in blender, but when I put it into the game, the truck appears, but the wheels, back suspension, driveshaft, and frame are messed up. However, if I hold Control, I can play with the jbeam. I will attach some pictures of the issue. I have plenty of specs as well.

Intel Core i5 - 7500
16GB DDR4 RAM
PNY GTX 1050 Ti 4GB Edition
Windows 10 Pro
500GB 850 EVO SSD


(When I tried to upload them I don't think it worked. I uploaded them to my server just in case.
Links:
1. http://j456796.us/files/1.png
2. http://j456796.us/files/2.png
3. http://j456796.us/files/3.png

 

Thanks for your reply. No, I don't. How would I do that?

 

if you look in the JBeam section of most other parts, you will see a "flexbodies" section.
for example, in the pickup body JBeam:

Code:

    "flexbodies": [
         ["mesh", "[group]:", "nonFlexMaterials"],
         //bodywork
         ["pickup_body", ["pickup_framefront", "pickup_cab", "pickup_firewall", "pickup_frontmeat", "pickup_lowermounts", "pickup_uppermounts", "pickup_shocktop"]],
         ["pickup_tubs", ["pickup_framefront", "pickup_cab", "pickup_firewall", "pickup_frontmeat", "pickup_lowermounts", "pickup_uppermounts", "pickup_shocktop"]],
    ],

as you can see, the "pickup_body" on the third line is the name of the mesh that is assigned. if you were to rename plane.001 to something like van_bus_roof in blender, then you were to replace "pickup_body" with "van_bus_roof" in the JBeam, the mesh would then appear.
the [group] part in the square brackets is what breakgroups and deformgroups in the JBeam affect this mesh, mainly so that, for example, a door can be torn off a vehicle, and become fully separated from the vehicle., so in your case, unless you wanted the walls and roof to tear apart individually, you would just assign the side, front, and back walls, as well as the roof and floor all to "van_bus_body". the lines of code might end up looking something like this:

Code:

    "flexbodies": [
         ["mesh", "[group]:", "nonFlexMaterials"],
         //bodywork
         ["van_bus_roof", ["van_bus_body"]],
         ["van_bus_wall_R", ["van_bus_body"]],
         ["van_bus_wall_L", ["van_bus_body"]],
         ["van_bus_floor", ["van_bus_body"]],
         ["van_bus_wall_back", ["van_bus_body"]],
         ["van_bus_wall_front", ["van_bus_body"]],
         ["van_bus_door", ["van_bus_door"]],
    ],

(as you can see with the door, that would get its own breakgroup in the JBeam so it can open.)

 

THANKS A TON! One more question, when I do that the seats show up. But they are orange and they slide on sharp turns. How do I fix that?