The product requires an installed copy of The Sims 3.

I'm honestly at my wits end, and pretty much don't know what else to do. I've searched pretty much every forum on this site. 

I've downloaded the base game sims 3. Yes, from games4theworld--successfully. Then I downloaded the expansion pack World Adventures without any problems. Yet, when I try installing any other packs from the complete collection it keeps giving me:

"This product requires an installed copy of The Sims 3. Please install The Sims 3 before installing this product."

...which I have. From here. 

Before anyone asks, yes I've uninstalled and installed the base game, and applied the manual patch. I didn't skips any steps from How to install The Sims 3 Correctly.

Sorry I'm being really specific here, but I'm honestly really desperate to find an answer/solution here. Thanks in advance.

UPDATE: In my Sims 3 game launcher I now get a message whenever I try to launch the game saying:

No game disc found! Please insert The Sims 3 World Adventures game disc before proceeding. 

...

Hello,

Welcome to the forum. 
That at least tells me that your base game is in fact installed properly,  and it should work.
That particular problem can be fixed by correctly copying the crack to the right location. If you can actually play after that, I don't see why you wouldn't be able to install the other expansionpacks.

I'll try installing the crack, and see if it works! Thanks.

Update: I put the crack in the right location and it worked! I can successfully launch the game now, thanks 

Although...still no dice on the other error. I still keep getting "This product requires an installed copy of The Sims 3. Please install The Sims 3 before installing this product."

I have no idea how to fix this, even though I was able to install World Adventure from the Complete Collection files...Any ideas on how this could have happened?

Hello,

I'm at a loss to be honest, but I'll find out if there's a topic about this.
Can you run the setup as administrator? To do this, right click on the setup and find the option in the drop down menu.

Okay, thanks for the effort. And I've tried to run as admin, but that didn't work either.

Hello,

Ok, that's unfortunate. Have you tried different packs?

Yes, I tried the different packs. 

When I was running CCleaner I saw in my registry that there was a 'Application Paths Issue' and a 'Missing MUI Reference'. These two problems keep showing up on the registry whenever I try to run the Sims3EP02Setup. 

...Could this be the problem preventing me from running the expansion packs? If so, what does it exactly mean? BTW, sorry for spamming this forum with questions--I just really want to get this fixed.

I wouldn't be surprised if that is the cause. But I'm not the right person to help with that, I'll relay your topic to one of my teammates.

Don't worry about "spamming" us, this is what we're here for

Haha, thanks!

Any solutions to this problem still?

You. Are. Awesome. 

It took some time I admit, but so worth it. Thanks so much! I'm able to download other packages now.