Custom Workflow Plugin has been registered on CRM Dynamics 4.0 but record has not been created, is this something wrong in the steps or code

Please help..

I have now registered the assembly and created a workflow also and tried to test it but is not working at all.

My requirement is to create a Car details (cir_cardetails) from Contact (contact) record (N: 1 relationship between Car details and Contact). Passing an input value in the custom workflow. I hoped that everything done well. After workflow is succeeded I checked that car details (mode) has not been created. Nothing has done, I have pasted the entire code on the below of image.

namespace CreateCardetailsRecord
{

//Given a name for the Custom workflow

    [CrmWorkflowActivity("Create Cardetails Record", "Utilities")]
    public partial class CreateCardetails : SequenceActivity
    {
        public static DependencyProperty modelProperty = DependencyProperty.Register("model", typeof(CrmNumber), typeof(CreateCardetails));

//This will use as input as  highlighted in the image       

[CrmInput("Model")]
        public CrmNumber model
        {

            get
            {
                return (CrmNumber)base.GetValue(modelProperty);
            }

            set
            {
                base.SetValue(modelProperty, value);
            }

        }

        public CreateCardetails()
        {

            InitializeComponent();

        }

        protected override ActivityExecutionStatus Execute(ActivityExecutionContext executionContext)
        {

            // Get the context service.
            IContextService contextService = (IContextService)executionContext.GetService(typeof(IContextService));
            IWorkflowContext context = contextService.Context;

            // Use the context service to create an instance of CrmService.
            ICrmService crmService = context.CreateCrmService(true);

            DynamicEntity entity = null;
            Guid contactId;

            if (context.InputParameters.Properties.Contains("Target") && context.InputParameters.Properties["Target"] is DynamicEntity)
            {
                // Obtain the target business entity from the input parmameters. (Getting the GUID of contact record)
                entity = (DynamicEntity)context.InputParameters.Properties["Target"];
                contactId = ((Key)entity.Properties["contactid"]).Value;

//Creating a lookup for Car Details and setting the GUID of contact

               Lookup lookup = new Lookup();
                lookup.Value = contactId;
                lookup.type = "contact";

                //Create an car details record which will be linked to the contact record
                DynamicEntity cardetails = new DynamicEntity("cir_cardetails");

                cardetails["cir_carsdetailsid"] = lookup;

                //Setting the picklist value of Model

                 Picklist modelPickList = new Picklist();
                 modelPickList.Value = model.Value;
              cardetails.Properties.Add(new PicklistProperty("cir_model",modelPickList));

               //Creating the car details record
                Guid carkey = crmService.Create(cardetails);
                 
            }
            return ActivityExecutionStatus.Closed;
        }
    }
}

I have pasted the entire code, am I missing something to achieve this (Should I need to include something else to make it done). All suggestion/feedback/assistance are welcome.