Point Cloud (Scatter) on TraceSOP

I found a script from [url]Create Point cloud from geometry. - General TouchDesigner Discussion - TouchDesigner forum, which is a scatter, generating point cloud on a surface. It works perfectly on geometry. However when I apply it to a traceSOP, it only generate points on the edge of the primitive.
dunno why it only creates points on edge.
Anyone has ideas on it, or anyone has a better way to do scatter?