We are planning to upgrade our P4T printers to QLN420. We currently use MC92N0g with Windows CE for printing via bluetooth on P4T.  The latest SDK was installed from the website but the bluetooth connection to QLN420 is not working. We used the sample code in the help document.  ZebraPrinterConnection thePrinterConn = new BluetoothPrinterConnection(theBtMacAddress);                               // Open the connection - physical connection is established here.                thePrinterConn.Open(); --- It fails here with the error "Failure to Connect"