Multiple Layer Triggers

Recently, someone posted to one of the forums or blogs - cannot really recall who, where, or when - that showed how to trigger layers from objects placed off stage using the timeline for that object to trigger the layer. I tried it a couple of times and it worked great. Now, I am working on a course where I want to have several layers appear based on the base layer timeline. I am using shapes placed off stage to trigger these layers from the base layer timeline - trigger seetings are: Action: Show layer, Layer: Layer Name, When: Timeline Starts, Object: Rectangle shape used as trigger object. Each layer properties has its Visibility set to "Hide other slide layers", and "Hide objects on base layer" checked, all other settings are unchecked.

The Base Layer, having a single image with no animation, plays fine, then the first layer triggers when the timeline reaches the shape object set to trigger it and plays its timeline that includes several images coming in and out based on the layers own timeline and then everything stops. The second, third and forth layers do not play. Any ideas out there as to what I am missing here? The layers are set to hide the base layer.