Reappearing Object

Hi Manar,

Thanks for sharing your project file! 

The reason why your object is reverting to its earlier state is because of the presence of this trigger: 

What's happening is that your object is changing to the 'IN BOX' state when the key is dropped into the box, and the immediately reverts to the normal state when you move your mouse away because of the present of the trigger. To fix this, you can add conditions to the triggers: 

As for your second design requirement , you can set the default state of your object to disabled, and only change it to normal when its corresponding lock is dropped on the correct target. 

Let me know if this works for you!