Why cant you use an escape orb when robbing keckleon?

You can't use an Escape Orb when robbing Keckleon in Pokémon Mystery Dungeon: Explorers of Time, Darkness, and Sky because the game mechanics prevent it.

The Escape Orb's effect only works in battle, and robbing Keckleon isn't a battle. It's a special event where you try to steal items from his shop. The game considers this a separate interaction, not a standard encounter.

Therefore, the Escape Orb's effect of teleporting you to the Pokémon Center isn't applicable in this scenario.

You can, however, use other methods to avoid getting caught by Keckleon, like using a Thief's Scarf or having a partner with the "Thief" ability.