First, the most common fixes:

• You have to wait till the the hovertext above the ball is telling you to drop something. Otherwise it will not let you.
• Make sure you're still holding the <ctrl> key when you are dragging the item over the Yellow Setup Ball. Even when you are releasing your left mouse button to drop the item, you should still be pressing the <ctrl> key.

If those didn't work, then we check for a more rare problem:

1. rightclick the Yellow Setup Ball and choose "Edit".
   
2. Look in the "General" tab.
3. Verify that it says "You cannot modify this object"? (if you can modify it, then please go back to the above fixes)
   
4. Rightclick your Command HUD and choose "Edit".
5. Go to the "Contents" tab and look for the "Happy Setup Ball".
   
6. Verify that the permissions (in brackets) include "no modify".

If 4. and 6. verifies that you have no modify rights, it means that the Second Life asset server has messed up the Yellow Ball, even though it was just sitting in your HUD minding its own business. This is a known Second Life issue that happens from time to time.

To fix, you need to get a new set.

• If you have run setup successfully before and have old "A used" toys in your inventory, you can update your Signature toy and get a fresh new set::
  • go to the Secret Warehouse,
    
  • hit the Update Switch, choose the correct toy.
    
  • wear the "A used" toy when it asks you to verify.
  • and it'll toss you new set. Run setup on this set, and trash the HUD with the borked Setup Ball.
• If this is the first time you are running setup on this toy (i.e. you just purchased it), then IM Lulu Ludovico. You can trash the HUD with the borked Setup Ball - it'll only confuse you.