System.Management.Automation error access denied

Question

System.Management.Automation class I use the c # PowerShell exchange programs that access the server, increase the tasks of e-mail accounts, a program error access denied;

 PSCredential credentials = new PSCredential(UserName, ssRunasPassword);
              //ExchangeUri=ExUri
                WSManConnectionInfo connectionInfo = new WSManConnectionInfo(ExchangeUri, "http://schemas.microsoft.com/powershell/Microsoft.Exchange", credentials);
                connectionInfo.AuthenticationMechanism = AuthenticationMechanism.Basic;

                Runspace runspace = RunspaceFactory.CreateRunspace(connectionInfo);
                runspace.Open();