I'm not quite sure I'm understanding the problem. But let me give it a go.... Sounds like you've got Dragon Valley downloaded. And the launcher *Says* its installed. However in-game it is not installed.
If this is the case, it's been suggested to try installing it via the in-game store, via shop mode. If you do not have this on. Click the 3 dots (...) at the Main Menu and select Options. Click the Gear Tab (General Settings) and enable shop mode.
If this doesn't work, another suggested tip is to uninstall the store items, and reinstall the items in groups, such as store worlds, lots, sets, and then the single items.
The links are below if you want to read up on what I searched out.
MrsFlynn
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The Sims 3 Dragon Valley Installation problems
http://answers.ea.com/t5/The-Sims-3/The-Sims-3-Dragon-Valley-Installation-problems/td-p/1549057Q: The installed world doesn't show up ingame
A: Sometimes the world doesn't get installed correctly. Try installing it again. Also if you tried installing through the launcher, try the ingame Store instead or the other way round.
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The Sims 3 : [FAQ] The Sims 3 Store
http://answers.ea.com/t5/The-Sims-3/FAQ-The-Sims-3-Store/td-p/333394Q: I installed my Store Content but it's not showing up in my game
A: Unfortunatly, the Launcher is a very unreliable tool. The more stuff you have, the greater the chance that files which have your stuff installed get messed up. If that starts happening to you. It's best ro reinstall all Store content, using this method:
Close your game and launcher
Go to documents\electronicarts\thesims3 and move the folder DCCache to your desktop (this is ALL your custom content, so if you have 3rd party content as well, you might wanna just move the *.ebc files as well as the missingdeps.idx)
If you have any worlds installed go to the installedWorlds folder and delete all Store worlds from there.
Go to the DCBackup folder and delete everything in there. You don't really need the stuff in here except for the ccmerged file but since you're reinstalling everything, it will be recreated.
Open the launcher and start reinstalling all store stuff in groups. Don't install all in one go. Start with the worlds, then lots, then sets and single items last.
When you're done, backup the DCCache folder. If the same starts happening again, go back to that backup so you don't need to start over. Make a backup from time to time, especially after you've installed worlds and lots.