Vertex D3D

I am working with d3d and have changed the coordinates for a 2d square (4 vertices) here is the code

Call DX.CreateD3DTLVertex(0, 0, z, 1, DX.CreateColorRGB(1, 0, 0), 1, 0, 0, TLVertexList(0))
Call DX.CreateD3DTLVertex(10, 0, z, 1, DX.CreateColorRGB(0, 1, 0), 1, 0, 0, TLVertexList(1))
Call DX.CreateD3DTLVertex(10, 10, z, 1, DX.CreateColorRGB(0, 0, 1), 1, 0, 0, TLVertexList(2))
Call DX.CreateD3DTLVertex(0, 10, z, 1, DX.CreateColorRGB(1, 1, 0), 1, 0, 0, TLVertexList(3))

However when i run the program it appears as a triangle.
I think i am supossed to give the coordinates in a certain right- to left patter or vice versa but i cant remember how? Can anyone help me?
Thanks

What is your rendering call, the bit which draws the primitives? I think it has something to do with that.