Azure - Mapping a virtual directory to file service share in cloud service

Question

Reference to : Mapping an Azure File Service CloudFileShare as a virtual directory on each instance of a cloud service

I encounter an issue when I am trying to create a virtual directory in Azure Cloud Service, and the virtual directory is mapped to Azure file service.

What I have done

1) use <Runtime executionContext="elevated" /> for webrole in in ServiceDefinition.csdef

2) in WebRole.cs I mount the drive (as described in http://blogs.msdn.com/b/windowsazurestorage/archive/2014/05/27/persisting-connections-to-microsoft-azure-files.aspx for PaaS) I also do it in application start.

    public static void MountShare(string shareName,
                          string driveLetterAndColon,
                          string username,
                          string password)
    {
        if (!String.IsNullOrEmpty(driveLetterAndColon))
        {
            // Make sure we aren't using this driveLetter for another mapping
            WNetCancelConnection2(driveLetterAndColon, 0, true);
        }

        NETRESOURCE nr = new NETRESOURCE();
        nr.dwType = ResourceType.RESOURCETYPE_DISK;
        nr.lpRemoteName = shareName;
        nr.lpLocalName = driveLetterAndColon;

        int result = WNetAddConnection2(nr, password, username, 0);

            if (result != 0 || result != 85)
//85 indicates the drive name is already used. in this scenario, it means the drive is already mapped.
        {
            throw new Exception("WNetAddConnection2 failed with error " + result);
        }
    }

3) In WebRole.cs, I create the virtual directories by the following,

app.VirtualDirectories.Add("/asset/cms", @"s:\cms");

4) In WebRole.cs, I use the following to make the AppPool run in the admin account I created for remote desktop,

applicationPool.ProcessModel.IdentityType = ProcessModelIdentityType.SpecificUser;
applicationPool.ProcessModel.UserName = appPoolUser;
applicationPool.ProcessModel.Password = appPoolPass;
applicationPool.ProcessModel.LoadUserProfile = true;

Problem:

I am unable to get anything from /asset/cms. It comes back with 500.19 if I try to access the files inside, and it says 'The requested page cannot be accessed because the related configuration data for the page is invalid.', and specifically it points to s:\cms\web.config which does not exist. When I remote to the cloud service instance, and open IIS mgr, I can see the virtual directories are created correctly.

I guess it's a permission problem. But I am not able to edit permission of the virtual directory since it's mapped to a network drive.

How can I solve this problem? -- Now the above problem is solved and the cloud service can access the file service share. But, new problem - is it possible to use the network_service identity to run the AppPool?