Semi-new to CRM. Need to develop a plug-in to stop a business process and stop from saving.

I have written a few scripts for CRM and I have experience with C#.

I am trying to write a plugin in the SDK. I have to conditions that I need to check in an Order entity. If neither of those conditions are met, the next step is to check a Product status in the Order Product entity, alert the user to the problem and not the let the user save until the issue is resolved. I feel like I am close, but I am missing something. Any help iis appreciated. Thank you in advance.

// <copyright file="PreOrderUpdate.cs" company="">
// Copyright (c) 2014 All Rights Reserved
// </copyright>
// <author></author>
// <date>5/9/2014 11:39:16 AM</date>
// <summary>Implements the PreOrderUpdate Plugin.</summary>
// <auto-generated>
//     This code was generated by a tool.
//     Runtime Version:4.0.30319.1
// </auto-generated>

using System.Windows.Forms;
using System.ServiceModel;
using Microsoft.Xrm.Sdk;

namespace NABC_CRM_Plugins
{
    

    /// <summary>
    /// PreOrderUpdate Plugin.
    /// Fires when the following attributes are updated:
    /// xrm_orderstagecode,xrm_ordertype
    /// </summary>    
    public class PreOrderUpdate : Plugin
    {
        /// <summary>
        /// Alias of the image registered for the snapshot of the 
        /// primary entity's attributes before the core platform operation executes.
        /// The image contains the following attributes:
        /// xrm_orderstagecode,xrm_ordertype
        /// </summary>
        private const string PreImageAlias = "preorder";

        /// <summary>
        /// Initializes a new instance of the <see cref="PreOrderUpdate"/> class.
        /// </summary>
        public PreOrderUpdate()
            : base(typeof (PreOrderUpdate))
        {
            base.RegisteredEvents.Add(new Tuple<int, string, string, Action<LocalPluginContext>>(20, "Update","salesorder", new Action<LocalPluginContext>(ExecutePreOrderUpdate)));

            // Note : you can register for more events here if this plugin is not specific to an individual entity and message combination.
            // You may also need to update your RegisterFile.crmregister plug-in registration file to reflect any change.
        }

        /// <summary>
        /// Executes the plug-in.
        /// </summary>
        /// <param name="localContext">The <see cref="Plugin.LocalPluginContext"/> which contains the
        /// <see cref="IPluginExecutionContext"/>,
        /// <see cref="IOrganizationService"/>
        /// and <see cref="ITracingService"/>
        /// </param>
        /// <remarks>
        /// For improved performance, Microsoft Dynamics CRM caches plug-in instances.
        /// The plug-in's Execute method should be written to be stateless as the constructor
        /// is not called for every invocation of the plug-in. Also, multiple system threads
        /// could execute the plug-in at the same time. All per invocation state information
        /// is stored in the context. This means that you should not use global variables in plug-ins.
        /// </remarks>
        protected void ExecutePreOrderUpdate(LocalPluginContext localContext)
        {
            if (localContext == null)
            {
                throw new ArgumentNullException("localContext");
            }

            IPluginExecutionContext context = localContext.PluginExecutionContext;

            Entity preImageEntity = (context.PreEntityImages != null &&
                                     context.PreEntityImages.Contains(PreImageAlias))
                ? context.PreEntityImages[PreImageAlias]
                : null;

            var orderType = Xrm.Page.getAttribute("xrm_ordertype").getValue();
            var orderStateCode = Xrm.Page.getAttribute("statecode").getValue();

            
             int totalCount;
                
            
            string fetchXml = null;

            if (orderType == "Fundraising" || orderStateCode == "Fufilled") return;

           
            try
            {
                {
                    strDebug = "101";

                    Entity orderEntity = service.Retrieve("salesorderdetail", orderId,
                        new ColumnSet(new string[] {"salesorderid", "New_Status"}));


                    EntityCollection unresolvedProductCount = service.RetrieveMultiple(new FetchExpression(fetchXml));


                    if (unresolvedProductCount.Entities.Count > 0)
                    {
                        totalCount = ((AliasedValue) unresolvedProductCount.Entities[0]["product_count"]).Value;
                    }

                    fetchXml = "<fetch version='1.0' output-format='xml-platform' mapping='logical'distinct='false'>";
                    fetchXml += "<entity name='salesorderdetail'>";
                    fetchXml += "<attribute name='productid'/>";
                    fetchXml += "<attribute name='productdescription'/>";
                    fetchXml += "<attribute name='priceperunit'/>";
                    fetchXml += "<attribute name='quantity'/>";
                    fetchXml += "<attribute name='extendedamount'/>";
                    fetchXml += "<attribute name='alesorderdetailid'/>";
                    fetchXml += "<order attribute='productid' descending='false'/>";
                    fetchXml += "<filter type=and>";

                    fetchXml += "<condition attribute='new_status' operator='in'>";
                    fetchXml += "<value>1</value>";
                    fetchXml += "<value>163650000</value>";
                    fetchXml += "</condition>";
                    fetchXml += "</filter>";
                    fetchXml += "</entity>";
                    fetchXml += "</fetch>";

                    unresolvedProductCount = service.RetrieveMultiple(new FetchExpression(fetchXml));


                    if (unresolvedProductCount.Entities.Count > 0)
                        MessageBox.Show(string.Format("Please up date all product status before continuing"));

                    throw new InvalidPluginExecutionException("Total: ");
                }
            }
            catch (e)
            {
                consoleLog("Error in " + e.message);
            }
        }
    }
}