Error in Script Task in Business Process

Hello!

I'm trying to make an integration with a digital signature call "Firmamex" and I trying to use the code that they provide in their SDK in a business process but i have error messages that dont let me publish the script task. 

This are the errors 

And this is the source code of the process. I already try to put a return true; at the end of the script task but stills send me the error. 

I hope you can help me.

namespace Terrasoft.Core.Process
{
 
    using Newtonsoft.Json;
    using SignmageSDK;
    using SignmageSDKCore;
    using System;
    using System.Collections.Generic;
    using System.Collections.ObjectModel;
    using System.Drawing;
    using System.Globalization;
    using System.Text;
    using System.Web;
    using Terrasoft.Common;
    using Terrasoft.Configuration;
    using Terrasoft.Core;
    using Terrasoft.Core.Configuration;
    using Terrasoft.Core.DB;
    using Terrasoft.Core.Entities;
    using Terrasoft.Core.Process;
    using Terrasoft.Core.Process.Configuration;
 
    #region Class: UsrfirmamexMethodsWrapper
 
    /// <exclude/>
    public class UsrfirmamexMethodsWrapper : ProcessModel
    {
 
        public UsrfirmamexMethodsWrapper(Process process)
            : base(process) {
            AddScriptTaskMethod("ScriptTask1Execute", ScriptTask1Execute);
        }
 
        #region Methods: Private
 
        private bool ScriptTask1Execute(ProcessExecutingContext context) {
            }
            public class Flow
                {
                    SignmageSDK.FirmamexServices signmageServices;
                    String base64;
                    String name;
 
                    public Flow(SignmageSDK.FirmamexServices signmageServices, String base64, String name)
                    {
                        this.signmageServices = signmageServices;
                        this.base64 = base64;
                        this.name = name;
                    }
 
                    public String request()
                    {
                        B64_doc b64_doc = new B64_doc { name = name, data = base64 };
 
                        JObject flujoEjemplo = JObject.FromObject(new
                        {
                            b64_doc = b64_doc,
                            stickers = new object[] {
                                new {
                                    authority = "SAT",
                                    stickerType = "line",
                                    dataType = "rfc",
                                    data = "ARCX9012226P8",
                                    imageType = "hash",
                                    email = "jhon@gmail.com",
                                    page = "0",
                                    rect = new Rect { lx = 226.45f, ly = 355.25f, tx = 397.75f, ty = 413.85f }
                                }
                            },
                            workflow = new object[] {
                                new {
                                    data = "ARCX9012226P8"
                                }
                            },
                            app2 = true
                        });
 
                        String flujoParams = flujoEjemplo.ToString(Formatting.None);
                        return signmageServices.request(flujoParams);
                    }
                }
            };
        }
 
        #endregion
 
    }
 
    #endregion
 
}