Ashley,
Did you accidentally click on Remove Box instead of Move Box To Wall?
In any case, here are the steps to add the PetFinder Box again to your Boxes Tab:
- Click on Applications button at bottom navigation bar, then click Edit
- At the Application edit page, locate the PetFinder.my application, and click on the Edit next to it
- A window will pop out, click on the Profile tab
- Click on the Add link at the Box section, and set it to be viewable to Friends of Friends
Once done, the PetFinder box should show again at the Boxes Tab, and you can try moving it to the Wall again.
Let me know if this works.