I ininstalled sims2/double deluxe because I didn't want it because I got the sims2pets. but I found out I have to have the sims 2 double deluxe to install the sims2pets. When I enter the installation code for the sims2deluxe it says it is the wrong code, but it is the code on the guide, please help

The sims 2 deluxe double code

DWP7-6SRE-GLNV-CNFT-YJHV

Make sure that you install Sims 2 Double Delux first. If you have that then make surethat you do not have any other sim games running.

Make sure there is no sims 2 content on your hard drive. if there are any EA folders on your comouter either in program files or in "my documents" delete them. Then try installing Double Deluxe again. Then you can install pets.
Pets is an expansion pack for the Sims 2 base game. Other expansion packs are University, Seasons, Free Time, Bon Voyage.Open for buisiness and Apartment Life...If you plan to get other expansion packs you should install them in order of their release to avoid future problems. Nightlife expansion is included with Double Deluxe.

A simple google search for sims 2 expansion packs will show you the correct order to install and descriptions of each pack and what they add to the game. Seasons lets your sims go fishing for example. They can cook the fish they catch, and also plant gardens, and experience the changing seasons from summer to winter.