Could not establish trust relationship for SSL/TLS secure channel — SOAP

For this type of error validate ur SSL Server by follwing code :

using System.Security.Cryptography.X509Certificates;
using System.Net.Security;

... then before you do request getting the error, do the following

System.Net.ServicePointManager.ServerCertificateValidationCallback = delegate(object sender, X509Certificate certificate, X509Chain chain, SslPolicyErrors sslPolicyErrors) { return true; };