Timelines - using objects to trigger

Hi. I am new to Hype and understand timelines and have created a simple animation. I am trying to figure out something that is likely super simple. I have an object on the Main Timeline, that is set up to play Another Timeline when moused over. That mouse over simply makes another object appear. But what's happening is that the object I want to appear only on the mouse over, appears in the Main Timeline, as well. I can't seem to ask it to be hidden in the Main Timeline. If I do, it also hides it in the other timeline. What am I missing?

Perhaps separate timelines for this isn't the proper method to have something appear only on mouse over??

Thanks in advance for any assistance.