How to upload attachment in a list using client object model?

Question

I need to upload attachment in a custom list using client object model. Below is my code. M able to add new item but nothing happening while adding attachments. Not any error even.

NetworkCredential credentials = new System.Net.NetworkCredential("username", "Password", "domain"); 

ClientContext cnt = new ClientContext("mossserver");                    

                    cnt.Credentials = credentials;
                    cWeb = cnt.Web;
                    cnt.Load(cWeb);
                    cList = cnt.Web.Lists.GetByTitle("Idea");
                    cnt.Load(cList);

                    itemid = InsertData();
                    cListItem = cList.GetItemById(itemid);
                    cnt.Load(cListItem);
                    FileSaveBinaryInformation fsbInfo = new FileSaveBinaryInformation();
                    fsbInfo.CheckRequiredFields = false;
                    fsbInfo.Content = btFileBytes;
                    //cListItem.File.CheckOut();
                    cListItem.File.SaveBinary(fsbInfo);
                    //cListItem.File.CheckIn("Comment here", CheckinType.OverwriteCheckIn);
                    cListItem.Update();
                    //cList.Update();
                    cnt.Load(cListItem);
                    cnt.ExecuteQuery();