Simple shadow, transparency problem

On these days of pixel shaders and those megathings, I'm trying to add a simple shadow, like those we saw years ago in many, many games (like resident evil). Most scenes in our 'educational game' are inside .dts (I know, I know, but our modeler hates quark), and this is is an old solution for shadows.

Here are some results:


Well, it seems to work. BUT (there's always a 'but'), seen from a different angle, the alpha transparency of the texture used for the shadow goes through the whole house model (it's a dts) and shows the terrain below it!! (there's even a cellar below the hall)



For the shadow, I saw how fxRenderObject was rendered, and added some code in player.cc and player.h. Here's the rendering part, in Player::renderImage:

if (mShapeInstance && renderPlayer && DetailManager::selectCurrentDetail(mShapeInstance)) {
   glPushMatrix();
   dglMultMatrix(&getRenderTransform());
   glScalef(mObjScale.x,mObjScale.y,mObjScale.z);
[b]
   glEnable(GL_BLEND);
   glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);

   // Enable Texturing.
   glEnable(GL_TEXTURE_2D);

   // Select the objects' texture.
   mDataBlock->mTextureHandle = TextureHandle(
         mDataBlock->mTextureName, BitmapTexture, true);
   glBindTexture(GL_TEXTURE_2D, mDataBlock->mTextureHandle.getGLName());

   // Set Colour/Alpha.
   glColor4f(1,1,1,1);

   // Calculate Quad Radius.
   F32 QuadSize = 0.50;

   glBegin(GL_QUADS);
   glTexCoord2f(0,0);
   glVertex3f(-QuadSize,+QuadSize,0.0);
   glTexCoord2f(1,0);
   glVertex3f(+QuadSize,+QuadSize,0.0);
   glTexCoord2f(1,1);
   glVertex3f(+QuadSize,-QuadSize,0.0);
   glTexCoord2f(0,1);
   glVertex3f(-QuadSize,-QuadSize,0.0);
   glEnd();

   glDisable(GL_BLEND);
   glDisable(GL_TEXTURE_2D);

[/b]
   if (mCloakLevel != 0.0) {
         glMatrixMode(GL_TEXTURE);
         glPushMatrix();

         static U32 shiftX = 0;...

Why is this happening? Could it be a sorting problem? Something related to .dts shapes and transparency?