Security excpetion while using SharePoint Object Model in Silverlight

Question

HEllo All, I am new to SharePoint and got stuck in one issue which is as follows:

I am creating New Folder in any existing directory in SharePoint Site via Silverlight.

The Code I Wrote is as :

 

        ClientContext clientContext;
        bool exists;
        List list;
        string folderName;
        public  void CreateFolder_ClientOM(string listName, string fName)
        {
           
            folderName=fName;
            clientContext = new ClientContext("http://eni-dev09:17025");
        
           

 

            Web web = clientContext.Web;
            list = clientContext.Web.Lists.GetByTitle(listName);

            clientContext.Load(clientContext.Site);

            string targetFolderUrl = listName + "/" + folderName;
            Folder folder = web.GetFolderByServerRelativeUrl(targetFolderUrl);
            clientContext.Load(folder);
            exists = false;

            ThreadPool.QueueUserWorkItem(new WaitCallback(abc));

          

        }
        void abc(Object stateInfo)
        {
            try
            {
                clientContext.ExecuteQuery();
                exists = true;
            }
            catch (Exception ex)
            { }

            if (!exists)
            {
                ContentTypeCollection listContentTypes = list.ContentTypes;
                clientContext.Load(listContentTypes, types => types.Include
                                 (type => type.Id, type => type.Name,
                                 type => type.Parent));

                var result = clientContext.LoadQuery(listContentTypes.Where
                  (c => c.Name == "Folder"));

                clientContext.ExecuteQuery();

                ContentType folderContentType = result.FirstOrDefault();

                ListItemCreationInformation newItemInfo = new ListItemCreationInformation();
                newItemInfo.UnderlyingObjectType = FileSystemObjectType.Folder;
                newItemInfo.LeafName = folderName;
                ListItem newListItem = list.AddItem(newItemInfo);

                newListItem["ContentTypeId"] = folderContentType.Id.ToString();
                newListItem["Title"] = folderName;
                newListItem.Update();

                clientContext.Load(list);
                clientContext.ExecuteQuery();

            }

 

        }

 

 

 

I Am Calling The Function as

 

CreateFolder_ClientOM("SLXAPLib","NEW"); 

 

 

 

 

I am Getting Security Exception......????

What May Be the Cause?

thanks in Advance.