ZebraPrinterLinkOs fails to Wrap printer object in my Android app

I am working with an iMZ320 printer using ZPL language. For some reason when I try to create a wrap for my printer object - ZebraPrinterLinkOs linkOsPrinter = ZebraPrinterFactory.createLinkOsPrinter(printer); - it fails and stops my application unexpectedly. Without using the wrapper my application works fine.

 

BTW, I tried the ConnectAndPrint Sample and the ZebraPrinterLinkOs instruction to create the wrapper works fine.

 

Hope somebody can guide me in the right direction.

 

Juan Carlos