customErrors mode Doesn't Work in my Server

I have been receiving the usual:

Server Error in '/' Application.

---

Runtime Error

Description: An application error occurred on the server. The current custom error settings for this application prevent the details of the application error from being viewed.

Details: To enable the details of this specific error message to be viewable on the local server machine, please create a <customErrors> tag within a "web.config" configuration file located in the root directory of the current web application. This <customErrors> tag should then have its "mode" attribute set to "RemoteOnly". To enable the details to be viewable on remote machines, please set "mode" to "Off".

<!-- Web.Config Configuration File --> <configuration> <system.web> <customErrors mode="RemoteOnly"/> </system.web> </configuration>

Good, I now how to solve this one, it's easy, you just have to go to C:\inetpub\wwwroot\wss\VirtualDirectories\80 and change the customErrors mode in the web.confing

Well it didn't work.

After trying a thousand things I found out that there's a more obscure web.config you need to change in SharePoint 2010, it's at c:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\14\TEMPLATE\LAYOUTS\

After changing the set there everything worked as expected.

It's funny it only happens in some servers I suppose it's one of the reasons why SharePoint is so funny.