I have put a question up in html as I think it helps to have images to ask the question. http://www.jamestrusler.co.uk/files/webglquestion/question1.html
Here is the covering question that can be seen within the html page too:
I fixed the problem with this:
obj[a].Transform.Group.Shape[b].vertexIndexBuffer = gl.createBuffer();
gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, obj[a].vertexIndexBuffer);