Rendering To Texture

Hi! I'm trying to render to a texture so i can play with shaders but all I'm getting is a black screen, and I get no errors :'( this is the first time I've done this so I cant tell whats wrong so here's the relevant code: width and height are 800 and 600, they are fine, I've looked:

	D3DXCreateTexture(D3DDevice, width, height, 1, D3DUSAGE_RENDERTARGET, D3DFMT_A8R8G8B8, D3DPOOL_DEFAULT, &renderTexture);
	renderTexture->GetSurfaceLevel(0, &renderSurface);

	//save original render target
	IDirect3DSurface9* originalRT;

	D3DDevice->GetRenderTarget(0,&originalRT);

	//set new render target - the texture
	D3DDevice->SetRenderTarget(0,renderSurface);
	
	D3DDevice->Clear(0, 0, D3DCLEAR_TARGET | D3DCLEAR_ZBUFFER, 0x00000000, 1.0f, 0);
	D3DDevice->BeginScene();

	//render stuff
	D3DDevice->EndScene();

	D3DXMATRIX World;
	D3DXMatrixTranslation(&World, 0.0f, 0.0f, 0.5f);

	//set original render target, the back buffer
	D3DDevice->SetRenderTarget(0,originalRT);
	D3DDevice->Clear(0, 0, D3DCLEAR_TARGET | D3DCLEAR_ZBUFFER, 0x00000000, 1.0f, 0);
	D3DDevice->BeginScene();

	D3DDevice->SetTransform(D3DTS_WORLD, &World);
	mat = *m_pMaterial->NoMaterial();
	D3DDevice->SetMaterial(&mat); //clear any set material
	D3DDevice->SetTexture(0,renderTexture);
	SAQuad->DrawSubset(0);
	D3DDevice->EndScene();
	D3DDevice->Present(0, 0, 0, 0);

SAQuad is supposed to be a screen aligned quad, here's the code I use to try and make it:

ID3DXMesh* CMesh::CreateScreenAlignedQuad(IDirect3DDevice9* m_pDevice, int width, int height)
{
	ID3DXMesh* Mesh = 0;
	HRESULT hr = 0;

	hr = D3DXCreateMeshFVF(
		2,					//Number of faces
		4,					//Number of vertices
		D3DXMESH_MANAGED,	//Options - Mesh will be placed the Managed memory pool
		Vertex::FVF,		//The FVF of the vertices of this mesh
		m_pDevice,			//D3D Device
		&Mesh);				//[OUT] created mesh

	if(FAILED(hr)){
		::MessageBox(0, "D3DXCreateMeshFVF() - FAILED", 0, 0);
			return 0;
	}

	// Fill in vertices of our tile
	Vertex* v = 0;
	Mesh->LockVertexBuffer(0, (void**)&v);


	// fill in the top face vertex data
				//  x		  y		  z
	v[0] = Vertex( 0.0f,	height,	0.5f,	0.0f, 1.0f, 0.0f, 0.0f, 1.0f ); //BL
	v[1] = Vertex( 0.0f,	0.0f,	0.5f,	0.0f, 1.0f, 0.0f, 0.0f, 0.0f );	//TL
	v[2] = Vertex( width,	0.0f,	0.5f,	0.0f, 1.0f, 0.0f, 1.0f, 0.0f );	//TR
	v[3] = Vertex( width,	height, 0.5f,	0.0f, 1.0f, 0.0f, 1.0f, 1.0f ); //BR

	Mesh->UnlockVertexBuffer();

	// Define the triangles of the box
	WORD* i = 0;
	Mesh->LockIndexBuffer(0, (void**)&i);

	// fill in the top face index data
	i[0] = 0; i[1] = 1; i[2] = 2;
	i[3] = 0; i[4] = 2; i[5] = 3;

	Mesh->UnlockIndexBuffer();

	// Specify the subset each triangle belongs to
	// There is just one subset
	DWORD* attributeBuffer = 0;
	Mesh->LockAttributeBuffer(0, &attributeBuffer);

	for(int a = 0; a < 2; a++)
		attributeBuffer[a] = 0;

	Mesh->UnlockAttributeBuffer();

	// Optimize the mesh to generate an attribute table.
	std::vector<DWORD> adjacencyBuffer(Mesh->GetNumFaces() * 3);
	Mesh->GenerateAdjacency(0.0f, &adjacencyBuffer[0]);

	hr = Mesh->OptimizeInplace(		
		D3DXMESHOPT_ATTRSORT |		//flag
		D3DXMESHOPT_COMPACT  |		//flag
		D3DXMESHOPT_VERTEXCACHE,	//flag
		&adjacencyBuffer[0],		//pointer to adjacency array of non optimized array
		0, 0, 0);					//not needed, so zero

	if(FAILED(hr))
	{
		::MessageBox(0, "OptimizeInplace() - FAILED", 0, 0);
		return false;
	}

	return Mesh;
}

I've no idea what's wrong, I'm getting no errors or warnings, even when I put DirectX into Debug mode. Any and all help will be gratefully received!! It's got to be something to do with my SAQuad, I tried rendering to the terrain and got this result, so it must be working... http://img256.imageshack.us/img256/3076/weird.jpg