read multiple user query - web api authentication

[miss786]

dear all, I am writing to seek help, as I am getting 401 authorized error (api/values), from using the following code:

protected override Task SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
{
AuthenticationHeaderValue authValue = request.Headers.Authorization;

        if (authValue == null || authValue.Scheme != BasicAuthResponseHeaderValue)
        {
            return Unauthorized(request);
        }

        string\[\] credentials = Encoding.ASCII.GetString(Convert.FromBase64String(authValue.Parameter)).Split(new\[\] { ':' });
        if (credentials.Length != 2 || string.IsNullOrEmpty(credentials\[0\]) || string.IsNullOrEmpty(credentials\[1\]))
        {
            //return Unauthorized(request);
            var resp = new HttpResponseMessage(HttpStatusCode.NotFound)
            {
                Content = new StringContent(string.Format("access denied")),
            };
        }
        ClaimRole user = repository.trial(credentials\[0\], credentials\[1\]);
        ClaimRole user2 = repository.unlim(credentials\[0\], credentials\[1\]);
        if (user == null || user2 == null)
        {
            var resp = new HttpResponseMessage(HttpStatusCode.NotFound)
            {
                Content = new StringContent(string.Format("access denied")),
            };
        }
        else
        {
            IPrincipal principal = new GenericPrincipal(new GenericIdentity(user.Username, BasicAuthResponseHeaderValue), new string\[\] { user.role });
            Thread.CurrentPrincipal = principal;
            HttpContext.Current.User = principal;
        }

        return base.SendAsync(request, cancellationToken);

    }

I have constructed two queries which output two different user groups, which can be seen from the user class code below:

    public ClaimRole trial(string username, string password)
    {
        var query = (from s in db.subs
                    join u in db.user on s.sUID equals u.uID
                    where s.sExpiryDate >= DateTime.Now &&
                    u.uUsername == username &&
                    u.uPassword == password
                    select u).FirstOrDefault();

        if (query != null)
        {
            // Build a user and add the appropriate Trial role