Irrlicht Engine

Hi,afecelis:
I got a problem like this:
I made a 3DS scene,and also made a glass with 50% opacity,then I loaded it to irrEdit,it looks fine before calculate the scene with "ambient light" option checked.But after I calculated the light,the opacity missing,and the glass looks like just a wall ...

Many thanks liger13,you are so kind
I'll try it.

That's a problem when I want to get a mesh from .irr scene.Here is the codes.

smgr->loadScene("anting.irr");
//=============================================
ISceneNode *scene_node=smgr->getSceneNodeFromName("rooms");
IAnimatedMesh *levelMesh=0;
if(scene_node && (scene_node->getType()==ESNT_MESH ...

many thanks:trivtn & dudMaN,you help me more.i got it.

There isn't a 20kdm2.bsp in example 7 of irricht that I download on Irricht website.
Can anybody offer me one?
Many thanks.