Convert files to byte array memory objects

ConvertFileToMemory.cs

public static string AddFilesToTransaction(RestService rs, string docNbr, string filePath, string fileName, string entity)
        {
            string result = "#UPLOADING DOCS";

            try
            {
                byte[] filedata;
                using (FileStream file = File.Open(filePath, FileMode.Open))
                {
                    filedata = new byte[file.Length];
                    file.Read(filedata, 0, filedata.Length);

                    //Add the file
                    Stream fileToAttach = new MemoryStream(filedata);
                    result = rs.PutFile(entity, docNbr, fileName, fileToAttach);
                }

            }
            catch (Exception msg)
            {
                result = msg.Message;
            }
            return result;
        }