Problem to link two layers

Hi all,
First I apologize for my bad english writing.
In a mocha-project (260 frames 720p50 DVCproHD) i will follow five windows on the first floor of a building (that pans out of the frame).
Now, I suppose having the correct X-spline on Layer_01 and after adjust the track the planar surface stays perfect between the four courners of the five windows (attachement Mocha 01.jpg) for the whole lenght.
When I create a second spline on Layer_02 in one of the parts of a window, move the corners of de planar surface to the corners of that part and link that layer to Layer_01 after two seconds (when the pan starts) the linked surface is drifting away (attachement Mocha 02.jpg).
What am I doing wrong?
I though I do the same as Steve Wright at the end in “Learn mocha: Chapter 1. What is Planar Tracking?”

Without seeing the shot, my best guess is that you’re tracking the whole window and the window’s reflection. You must keep in mind that reflections are giving the planar tracker information on a different plane than the one you are trying to track. Try just tracking the outside edge of the window by cutting out the middle of the window on the same later using the “add x-spline” tool.
Please see more details here and let me know if that’s the problem:
If that doesn’t work, please email me and I can take a look at the shot and see what’s going on.

Now, it works veryy well.
Thank you, Mary !