Ok, first, “the other lights in the room come on” are they on the scene you want to dim?
second, it sounds like the scene you are activating does not have a toggle scene created. To create one, go to agents. Then advanced lighting scenes. Then select the scene you are activating with the binding to a button. Then, along the top you will see a drop down menu for a toggle scene.
clock the button that says, “ create toggle scene”.
Hope this helps.