Connect to ECL via .NET giving permission issue

Trying to connect to Tridion via ECL WCF api but getting permission issue. Here is my code:

EndpointAddress eclServiceEndpoint = new EndpointAddress("net.tcp://localhoast:2660/ExternalContentLibrary/2012/netTcp");
NetTcpBinding binding = new NetTcpBinding
{
    MaxReceivedMessageSize = 2147483647,
    ReaderQuotas = new XmlDictionaryReaderQuotas
    {
        MaxStringContentLength = 2147483647,
        MaxArrayLength = 2147483647
    }
};
// ecl service client
var eclServiceClient = new SessionAwareEclServiceClient(binding, eclServiceEndpoint);
eclServiceClient.Impersonate(@"domainuser");

I am getting a permission error in the last line. I have added impersonation user to server, restarted COM+ services and IIS but nothing works.

What am I doing wrong? We are using Celum as ECL and we have DXA 1.9 (Web 8.5).