I know this is an extreme necro-post but I was having the same issue and had some additional information to contribute.
I had the exact same issue with two items from the exchange but I own and had installed every expansion pack and stuff pack. My items wouldn't install until I activated (checked) the appropriate expansion pack in the Sims 3 Launcher "Expansions & Stuff" menu and then it installed properly. So if you have the expansion pack installed and are still having the issue make sure it is activated in the launcher.