can't install items purchased from sims 3 site

As far as I know if you cant purchase something individually it will say so on the item and tell you  have to buy the set/or world. What did you buy and what are you trying to install?

I purchased a wicker bookshelve and wicker basket. I don't remember which set it was included in, I was clicking on sets and compilations and looking through them. If i was allowed to purchase and item i liked without buying the complete set I would do so. These two items are the only two that have downloaded to my launch box, but will not install. I keep getting the message that i must purchase the complete set it is connected to. But I don't understand why I was allowed to purchase them separately in the first place, if that was the rule? Normally, if you can't individually buy items it will not allow you to purchase them that way. I could have used them points on other items.

Is this from the Island Escape Compilation? This is the only wicker I could find. I see the baskets are 15 sim points but I dont see a bookshelf

Also have you tried downloading these items from your purchase history and not right after you buy the items? Trying to download right after you buy an item does not always work why you should download from purchase history.

Could you post the exact wording of that message you're getting or post a screenshot ?

I've never ever come across anything from the Store that can't be installed on it's own if you have the download separately. There's certain items that you can't uninstall on it's own cause the came with a world.