Not able to print from Android BT using LinkOS

Hi

 

I have a Zebra ZQ510 BT printer, and i am not able to print using the sdk.  I can connect and get a ready to print status, but when i write the zpl via the connection it does nothing.  The Icons on the printer do blink but nothing is printed.  Here is my code.  Can someone please help as i am lost into what i am doing wrong.

 

var sb = new StringBuilder();                         sb.AppendLine("^ XA");                         sb.AppendLine("^ LH 1000,100");                         sb.AppendLine("^ FO20,10");                         sb.AppendLine("^ ADN,50,30");                         sb.AppendLine("^ FD'''From:''' ABC Company^ FS");                         sb.AppendLine("^ LH0,0");                         sb.AppendLine("^ XZ");                                               var zpl = sb.ToString();                         var printer = new ZebraPrinter();                           var result = printer.PrintIt(zpl); 

 

public class ZebraPrinter     {         private string printCommand;         LinkOS.Plugin.Abstractions.IConnection connection;         const string tag = "BasicPrintApp";           public ZebraPrinter()         {         }           // This is THE method :)         public string PrintIt(string printingString, string mac = null)         {               printCommand = printingString;               if(connection == null)             {                 if (mac == null)                     connection = ConnectionBuilder.Current.Build("BT:24:71:89:55:20:B0");                 else                     connection = ConnectionBuilder.Current.Build("BT:" + mac);             }               if (!connection.IsConnected)             {                 connection.Open();             }                         if ((CheckPrinterStatus(connection)))             {                 connection.Write(Encoding.ASCII.GetBytes(printCommand));                                Thread.Sleep(500);             }             else             {                 return "Printer is not ready.";             }               connection.Close();                          return "Printed Ok";         }           private bool SetPrintLanguage(LinkOS.Plugin.Abstractions.IConnection connection)         {             string setLanguage = "! U1 setvar \"device.languages\" \"zpl\"\r\n\r\n! U1 getvar \"device.languages\"\r\n\r\n";             byte[] response = connection.SendAndWaitForResponse(Encoding.ASCII.GetBytes(setLanguage), 500, 500);             string s = Encoding.ASCII.GetString(response);             if (!s.Contains("zpl"))             {                 Log.Debug(tag, "Not a ZPL printer.");                 return false;             }             return true;         }           private bool CheckPrinterStatus(LinkOS.Plugin.Abstractions.IConnection connection)         {                         IZebraPrinter printer = ZebraPrinterFactory.Current.GetInstance(connection);             var lang = printer.PrinterControlLanguage;                         IPrinterStatus status = printer.CurrentStatus;             if (!status.IsReadyToPrint)             {                 Log.Debug(tag, "Printer in Error: " + status.ToString());             }             return true;         }     }        private bool CheckPrinterStatus(LinkOS.Plugin.Abstractions.IConnection connection)         {                         IZebraPrinter printer = ZebraPrinterFactory.Current.GetInstance(connection);             var lang = printer.PrinterControlLanguage;                         IPrinterStatus status = printer.CurrentStatus;             if (!status.IsReadyToPrint)             {                 Log.Debug(tag, "Printer in Error: " + status.ToString());             }              Link