Document requires at least one signing party

[Sreevalli]

Hi,
I'm using Below code to send my existing template, that template is having one text field and 1 signature field. i tried for other templates also but getting same issue. did i missed any parameters?? can you please help me.

public static void prepackage_and_send_templates(string[] templateGUIDs)
{

        XDocument response;

        // Prepackge a Template to prepare it for sending, sets a Callback URL so we can get listen for callbacks 
        //  when the Documenet gets created, viewed, and completed (all signers signed)
        string guid = rightSignatureApi.PrepackageTemplate(templateGUIDs, "http://127.0.0.1:8888"); // my template guid is "a_2764708_260803f29d634c6880cbc6af6739adad"
        Console.WriteLine("got GUID:" + guid);


        // Filling in the info for Document Roles
        Dictionary<string, RightSignatureAPI.RoleUser> roles = new Dictionary<string, RightSignatureAPI.RoleUser>();
        roles.Add("Document Sender", new RightSignatureAPI.RoleUser("Bryan Currier", "[email protected]", true));
        roles.Add("Project Manager", new RightSignatureAPI.RoleUser("Sreevalli Balleda", "[email protected]", true));

        // Send document with fields filled out
     //   (guid, subject, roles, mergeFields, tags, description, callbackURL, expires_in)
        //response = rightSignatureApi.SendDocument(guid, "Test Development", roles, mergeFields, tags, "Please sign this document", null, 2);//"http://127.0.0.1:3000"
        response = rightSignatureApi.SendDocument(guid, "Test Development", roles, null, null, "Please sign this document", null, 2);//"http://127.0.0.1:3000"
        Console.WriteLine("Response received is:\n" + response.ToString());
    }