How to make a 3d floor?

I'm using Doombuilder 2 and GZDoom.
Here's my script, (note: this is my first attempt)

Sector_Set3dFloor(98, 1, 16, 0, 8);

I followed the wiki to the best of my comprehensive ability.

Manhunt21 said:

script

There's your problem right there. The special is attached to a line in the control sector, not in a script.

Oh...
:|

What's the control sector, the one where I want the 3d floor?

1. Give the sector (the one where you want the 3D floor to appear) a new tag.
   
2. Create a control sector (a new sector outside your map - most mappers make it triangular to keep the number of linedefs low).
   
3. The control sector must have the following properties:

   ZDoom Wiki said:
   The ceiling of the control sector will be the floor of the 3D floor and the floor of the control sector will be the bottom of the 3d floor.

4. Set the linedef action 160:Sector_Set3dFloor to one of the linedefs that surrounds the control sector. Its middle texture will be used for the sides of the 3D floor (unless you specify it differently with the flags argument).
   
5. Set the lindef action's first argument to the sector tag of the sector containing the 3D floor (the one from step 1).
   
6. Set all the other arguments the way you want them to be (you can read more about what each argument does here on the ZDoom Wiki).

Alright, it's created. One problem. It doesn't get a texture. It's just see-through.

http://zdoom.org/wiki/3D_floor

alpha: Specifies the translucency of the 3D-floor.

If you don't know, alpha 255 is opaque, alpha 0 is transparent.