This feature cannot be used because the default provider type could not be determined to check whether it is a trusted provider

Hi,

We are trying to configure  external users from SQL db with custom .NET provider and we get error:

You can use this feature only when the default provider is a trusted provider.  If you are a server administrator, you can make a provider a trusted provider by adding the provider type to the trusted providers list in the Administration.config file.  The provider has to be strongly typed and added to the GAC.

What I have done:

Added line:
<add type="Microsoft.SharePoint.Administration.Claims.SPClaimsAuthMembershipProvider, Microsoft.SharePoint, Version=14.0.0.0, Culture=neutral, PublicKeyToken=71e9bce111e9429c" />

In C:\Windows\System32\inetsrv\Config\administration.config

Also checked that we have .NET v2 as DefaultAppPool.

Is it strange that on other sites in IIS i don't get this error for custom .NET membership provider, just in this site. I can not delete this site because it is part of SharePoint.

Please help,
Thanks