Getting Vertex Positions

Hi Im working on making a rigid terrain using the Tokamak physics SDK. I want to read in the verticies from a DirectX Mesh and load them into the Tokamak terain vertices. Ive got most of it working but heres the problem: I have defined a custom vertex format containing only the position of each vertex in my 3d model:

struct CUSTOMVERTEX
{
	float x,y,z;   // The untransformed position for the vertex.
};

#define TERRAIN_VERTEX (D3DFVF_XYZ)

then i wrote a method to access the mesh loaded in:

void PhysicsTerrain::BuildTerrainMesh()
{

	base->D3dDevice->SetFVF(TERRAIN_VERTEX);

	// The array of vertices
	neV3* triVertices;
	// The array of triangles
	neTriangle* triData;

	int i, j;

	// Access the parent Mesh (already loaded)
	ID3DXMesh* parentMesh = m_Mesh->getParentMesh()->m_Mesh;   

        // Set the number of vertices into the triMesh
	triMesh.vertexCount = parentMesh->GetNumVertices();
	triMesh.triangleCount = parentMesh->GetNumFaces();


	CUSTOMVERTEX *pVertex = NULL;

	if(FAILED(parentMesh->LockVertexBuffer(D3DLOCK_READONLY, (BYTEVOID**)&pVertex)))
	{
		base->messageBox(NULL,"Failed to Lock Vertex Buffer","Physics Terrain");
		return;
	}

	triVertices = new neV3[triMesh.vertexCount];

	for(i = 0; i < triMesh.vertexCount; i ++)
	{
		triVertices.Set(pVertex->x,pVertex->y,pVertex->z);
		sprintf(base->buffer,"X %f, Y %f, Z %f \n Vertex: %d",pVertex->x,pVertex->y,pVertex->z,sizeof(pVertex));
		base->messageBox(NULL,base->buffer,"Vertex Data");
		pVertex ++;
	}
	parentMesh->UnlockVertexBuffer();


	// Set the vertices into the triMesh
	triMesh.vertices = triVertices;

.......... index buffer stuff (working) ......

	// Tell the simulator about our mesh
	base->physicsManager->PhysicsSimulator->SetTerrainMesh(&triMesh);
}

the problem is that although im specifying that it use my custom vertex format it is loading the texture coordinates and normals from each vertex. How do i read ONLY the position from the vertex?