Update plugin not working

I am new to plugins and I am trying to create a simple update plugin to get my project started. All I want to do is update the "description" field on contact with a string "test". I got this to work, but then I changed something in the code to try something new. Now I can't get it to work again.

I am using the Plugin Registration Tool and have set up the step like in the picture. When I do some changes in the "crmn_ourdescription" field nothing seems to happen. I have tried both pre- and post-operation.

What is wrong here?

using System;
using Microsoft.Xrm.Sdk;

namespace CalculateScorePlugin
{
    public class CalculateScore : IPlugin
    {
        public void Execute(IServiceProvider serviceProvider)
        {
            IPluginExecutionContext context = (IPluginExecutionContext)serviceProvider.GetService(typeof(IPluginExecutionContext));
            IOrganizationServiceFactory servicefactory = (IOrganizationServiceFactory)serviceProvider.GetService(typeof(IOrganizationServiceFactory));
            IOrganizationService client = servicefactory.CreateOrganizationService(context.UserId);
            {
                if (context.InputParameters.Contains("Target"))
                {
                    if (context.InputParameters["Target"] is Entity)
                    {
                        Entity entity = (Entity)context.InputParameters["Target"];
                        if (entity.LogicalName == "contact")
                        {
                            if (entity.Attributes.Contains("description"))
                            {
                                try
                                {
                                    //entity["crmn_ourdescription"] = "Test";
                                    entity.Attributes["description"] = "Test";
                                   
                                    //entity.Attributes["crmn_ourdescription"] = "Tester";


                                    client.Update(entity);
                                }
                                catch (Exception ex)
                                {
                                    throw new InvalidPluginExecutionException("An error occured in the plugin:", ex);
                                }
                            }

                        }
                        else return;
                    }
                }
            }

        }
    }
}