Can't able to delete inbox mail from gmail account using OpenPop.Net

Question

I'm using OpenPop DLL and it's working great for my project but i'm getting on issue when i'm using with Gmail Account. I'm not able delete the Email from Gmail after reading. I'm using following code and latest OpenPop DLL :

                using (OpenPop.Pop3.Pop3Client pop3Client = new OpenPop.Pop3.Pop3Client())
                {
                    // Connect to the server
                    pop3Client.Connect(
                        ConfigurationManager.AppSettings["host"],
                        Convert.ToInt32(ConfigurationManager.AppSettings["port"]),
                        Convert.ToBoolean(ConfigurationManager.AppSettings["useSsl"]));

                    // Authenticate ourselves towards the server
                    pop3Client.Authenticate(
                        ConfigurationManager.AppSettings["username"],
                        ConfigurationManager.AppSettings["password"],
                        AuthenticationMethod.UsernameAndPassword);

                    // Get the number of messages in the inbox
                    int messageCount = pop3Client.GetMessageCount();
                    if (messageCount > 0)
                    {
                        // We want to download all messages
                        allMessages = new List<Message>(messageCount);

                        // Messages are numbered in the interval: [1, messageCount]
                        // Ergo: message numbers are 1-based.
                        // Most servers give the latest message the highest number
                        for (int i = messageCount; i > 0; i--)
                        {
                            allMessages.Add(pop3Client.GetMessage(i));
                        }

                        // Process all the messages and save in database
                    }
                    // On successful insert in database, delete the same message from email server
                    pop3Client.DeleteAllMessages();
                    pop3Client.Disconnect();
                    pop3Client.Dispose();
                }

Can you please let me know if there's anything wrong i'm doing in code? You help will be appreciable.