When GameObject (A) hits (B) it instantiates (C) en moves (B) in front of a timeline.
When you move the timeline (B) moves towards (A) and hopefully triggers to instantiate (C) en move (B).
But i only get it to trigger once. Does someone know why?
No, no one knows why because you didn’t give us any information to work with. This is not the psychic hotline…
Having to make a lot of assumptions here, but based On the information you’ve given, you might be using an ‘OnTeiggerEnter()’ method or similar. Which only fires on the first frame that the collision occurs. I forget what it’s called but there are other similar methods that trigger every frame that the collision is happening, and another that triggers on the first frame that the collision ends. These may be more useful to you.