Your post title = importing max successfuly!, so i believe you havent imported max models successfuly into MED or WED.

Btw, before you can use models made with 3ds max, you need to find and understand a workflow between max and MED in order to use .mdl files in the engine.

Probably you are not seeing the model in MED preview because of two reasons:

1 - you havent pressed the zero key in order to free the default camera, or;

2 - the relative dimensions of the model made in max (units) are very small and you cant see it in MED or in the engine;

3 - even if you see the model in Med preview or the in engine, probably you dont have textures and no animation;

The link above tells you possibles workflows to "importing max successfuly" into 3dgs engine.