Sims 3 dragon valley - 16 digit code needs to be 20 digits

Did you try to redeem the game and not registered.

For register you need 20

Redeem needs 16.

In case it doesn\t work on redeem, try to contact support so they can give you a new key

did you buy it from the sims store? It should be in your download purchase history, You need to register the 16 code to get the extra content. You get it here

http://www.thesims3.com/

the codes redeemed on your the sims3 account once redeemed you download the world from your the sims3 purchase history see the FAQ as there is instructions on how to redeem the codes

FAQ  http://answers.ea.com/t5/The-Sims-3-Store/Guide-Sims-3-Store-Worlds/td-p/1589911

Follow these steps to redeem your code

1. Go to thesims3.com and log in with your account
2. Go to your account page: https://store.thesims3.com/myAccount.html (site will ask for your password again) 
3. Click on Redeem a Code 
4. Enter the 16-letter code, accept the Policies and click on Redeem
5. Go to your purchase history to download the world (make sure your game is updated to the newest version)

OR

1. Go to thesims3.com and log in with your account
2. Go to the general redeem a code page: http://www.thesims3.com/incentive/generalredeem.html
3. Enter the 16-letter code (this is not for 20-letter codes) and click on Submit
4. Go to your purchase history to download the world (make sure your game is updated to the newest version)