If you want to track multiple layers or layers with an effect you must first pre-compose them. If you want to use Mocha then you have to Pre-render them. If you have a camera move you can use expressions to analyze the move but since we know very little about your composition I can't begin to suggest what you should be doing. Here's how to easily tell us all about your comp. Select all of the layers in the time line that are important to the shot. Press the "u" key twice. This will reveal all modified properties. If an effect is applied to a layer that may be causing problems then make sure the Effects Control Panel is visible for that layer or layers. Now take a screenshot. If you need to reduce the size of your Composition Panel to 50% or even 25% to fit things in do that. Now drag the screenshot to the Reply field on this forum and describe in detail what you are trying to do.
Hi Rick, sorry to react late to your message; I'm testing suggestions made by the forum of videocopilot to which I presented my problem too. I haven't finished using their ideas but as soon as I draw conclusions of their suggestions I'll let you know and eventually develop here my problem as you suggested it.
I found the solution to my problem. In fact I had watched a tutorial which explained this with a green screen and had completely forgotten it. Here is the link
to the video. Its the equivalent of linking to the classic link to a null in 2D; there you take advantage of being able to use group null. I just had to take out the basin from the temple and create a group for its own and then create the group null and apply to the clip the position of the null. So the temple is finished and I"ll go on to another part of my scenario! Thanks anyway. Claude