I don't understand...I created other objects and I had no problem, but with this f.... bed, I'm going crazy.
I have the last version of tools and milkshape plugins and bla bla bla...I tried to create the bed starting by 2 different cloned beds, just to be sure that the original mesh wasn't the problem.
I only changed the structure - absolutely didn't touch the animated parts of the bed (cover pillows&co.) and this is the result

in milkshape, when I import the original mesh, it has a strange aspect, as you can see.

Could you tell me where my mistake in the procedure is? thank you so much

I'm just now working on a single bed and the mattress also has that same issue in Milkshape. Although in game mine is working fine and appearing fine. I've not tried a double bed.

The easiest way I've found to separate the frame mesh from the mattress, is to select it in the joints tab. This way I identify which joint it needs to be reassigned to plus I don't accidentally select any other vertexes.

thank you but I am very carefull when I delate the vertexes and assign the vertexes of the new mesh at the same joint...I don't know, I am really confused...could it be a problem with my video card? mumblee

The display issue in MilkShape is caused by the close proximity of the two sides of the cover. They are two different sets of faces, one turned up and one turned down. Because of minor variations in the coordinates, in some locations the bottom side is above the top side.

MilkShape has a display option "Draw Backfaces" that you access (for each window) via a right-click menu. In your case, you have that option selected, and the bottom-side faces that appear above the topside are drawn in black. If you turn that option off, those faces will be invisible (from the topside).

I am not sure if this is the problem with the bed in-game or not. The game renders backfaces as invisible, so it should render like that.

thank you
I try this...and I will tell you if it works