Multiple model targets used one at a time

Hi,

I am trying to make an app in Unity that tracks one model target at a time to trigger a fullscreen video. I have three videos and three model targets corresponding to them made in Model Target Generator. I want the app to recognize a model target and show the corresponding video. This works fine with one model target in the scene: I can track one target and the video appears, but when I try to add one more model target in the scene I get this error message "Exception in callback: Failed to activate observer for behaviour "myTarget"". Is there any way to solve this? I don't need to be able to track all Model targets at the same time but I need there to be possible to switch between the targets the app is searching for. Is there any way to do this with Vuforia model targets?

Any help would be greatly appreciated, thank you in advance!

I am using Vuforia 10 with Unity 2020.3.19f1 More detailed error message in the attached photo.