Now studio Ruffian Games has sorted the trouble out which was to do with "mastering the DLC package." Delete and re-download the DLC.
"The Crackdown 2 DLC Toy Box was initially released with a series of bugs caused by incorrect configuration of the DLC package," Ruffian on their studio forums. "These issues were caused by problems mastering the DLC package. They have now been resolved with a new version of the Toy Box DLC that Microsoft has released".
The Toy Box DLC comes in both free and premium versions with the latter adding some extra goodies. The free version comes with the much sought after 'Keys to the City' mode which lets you have crazy fun with the singleplayer game - like cheating.