Irrlicht Engine

Is it supposed to work with irr 1.8.1?

Did everything right( I think ) and don't see any results, tried all the provided hlsl files. (using dx9)

How does it know when to use which texture?

I have applied it to extracted marching cubes mesh, but at the moment I don't even know what to research.

Basicly, I'm trying to apply texture to a piece of mesh based on corresponding voxels value.

I'm using dx9 and HLSL and I'm trying to set variable in a shader, but it says: "HLSL Variable to set not found: 'mWVP'. Available variables are:"

This is my shader code:
float4x4 mWVP;

struct v_out
{
float4 pos : POSITION;
};

v_out v_main( float4 pos : POSITION )
{
v_out Out = (v_out)0 ...