The ‘Referer’ header must be modified using the appropriate property or method

"I am getting an error that says 'The 'Referer' header must be modified using the appropriate property or method'. I don't understand the meaning of this. The code seems pretty simple but i do not understand why it isnt working for me. Does anyone know what the cause of this is. Here is a copy of the C# code that I am using to make the request. var request = (HttpWebRequest)WebRequest.Create(url);

	var request = (HttpWebRequest)WebRequest.Create(url);
	request.Headers.Add(""Proxy-Authorization"", ""Basic "" + encodedApiKey);
	request.Referer = REFERERURLROOT + productSku;
	request.Proxy = myProxy;
	request.PreAuthenticate = true;
	request.AllowAutoRedirect = false;
	request.ServerCertificateValidationCallback += (sender, certificate, chain, sslPolicyErrors) => true;

	var apiresp = request.GetResponse();"