Authentication section in web.config is not working

Whatever I do, I can't set authentication section in web.config, it is always getting the default values. For example I have this:
<authentication mode="Forms"> <forms name=".AUTH" defaultUrl="~/Pages/Home.aspx" loginUrl="~/Login/Home.aspx"></forms> </authentication>
But when I try to log in, the defaultUrl takes his value by default(/default.aspx) instead of the value I set. I tried to removing the authentication section and add it again, it didn't work, as well I tried to change the name of the Home.aspx to default.aspx and put it in root, and it redirect me to /default.aspx so I interpret that it authenticates me correctly, but I still as anonymous user so it doesn't work on this way neither. I tried to check it with other web application and it worked perfectly and I don't know what else try to fix this error, because few days ago it was working perfectly until it stopped to wor ...