Delete or Update is not executed

Below is the update functionality at the server side using web forms (c#) Asp.Net.
Event creation is accomplished (the event appears on display and in database) but when deleting a red line marks event name on display and the event is not deleted from the database. Refresh will return the event to its original place. The same happens with update, refresh returns the previous page without changing the display or the database values.

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public void ProcessRequest(HttpContext context)
{
context.Response.ContentType = “text/xml”;

        var action = new DataAction(context.Request.Form);
        var data = new SampleDataContext();
        try
        {
            //create event object from request
            var changedEvent = (T656Event)DHXEventsHelper.Bind(typeof(T656Event), context.Request.Form);

            switch (action.Type)
            {
                case DataActionTypes.Insert: // define here your Insert logic
                    data.T656Events.InsertOnSubmit(changedEvent);
                    //action.TargetId = changedEvent.EventId;
                    break;
                case DataActionTypes.Delete: // define here your Delete logic
                    changedEvent = data.T656Events.SingleOrDefault(ev => ev.EventId == action.SourceId);
                    data.T656Events.DeleteOnSubmit(changedEvent);
                    break;
                default:// "update" // define here your Update logic
                    var updated = data.T656Events.SingleOrDefault(ev => ev.EventId == action.SourceId);
                    //update "updated" object by changedEvent's values, 'id' should remain unchanged
                    DHXEventsHelper.Update(updated, changedEvent, new List<string>() { "id" });
                    break;
            }
            
            data.SubmitChanges();
        }
        catch (Exception a) 
        { 
            action.Type = DataActionTypes.Error; 
        }
        context.Response.Write(new AjaxSaveResponse(action).ToString());
        //context.Response.Write(new AjaxSaveResponse(action).Render());
    }

What type do you use for an ID of event? if it’s not int, you need to specify it on creation DataAction object: var action = new DataAction<Guid>(context.Request.Form);
If this not helps - please put a breakpoint at this line

action.Type = DataActionTypes.Error; 

Anc check an error message in an exception object