C# – visual studio 2012 debug for asp.net not working using IIS7

I can´t run visual studio 2012 debug for asp net using IIS7.

I have already tried the following

ASP NET Settings in IIS

.NET Compilation: Changed Default Language to c#

IIS Settings

ASP:

• Changed script Language to c# (manually)
• Enable Client-side debugging: true
• Enable Server-side debugging: true

Script
– Language: c#

Also I am using Asp Net v4.0 app pool

Is there any other settings I can change to try make it work?

EDIT:

My user is part of Debbuger Users

The error is the following:

Unable to start debbuging on the web server. The web server is not configured correctly. See help for common configuration erros.

EDIT 2:

This is the log

Software: Microsoft Internet Information Services 7.5
Version: 1.0
Date: 2012-12-18 11:29:55
Fields: date time s-ip cs-method cs-uri-stem cs-uri-query s-port cs-username c-ip cs(User-Agent) sc-status sc-substatus sc-win32-status time-taken
2012-12-18 11:29:55 ::1 DEBUG /tgpwebged/debugattach.aspx - 443 - ::1 - 403 7 5 43

EDIT 3:

I have manually configured the compilation element in web.config. This is the actuall config:

<compilation batch="true" debug="true" defaultLanguage="C#" explicit="false" 
maxBatchGeneratedFileSize="10000" maxBatchSize="10000" 
numRecompilesBeforeAppRestart="100" strict="false" 
tempDirectory="C:\Windows\Temp" urlLinePragmas="false"> </compilation>

Also just for test purpose changed the user ASP NET V4 app pool runs under to my account. Not the SYSTEM.. my personal account. No success yet.