I'm pretty sure that the Generic/Text Only Printer Driver wont support Barcodes.
Most Barcoding that I've run into since USB started being used is centered around using Windows Printing and True Type Fonts. The Barcode itself is a Font that is used to display the bars instead of text that it represents. Typically a Windows Driver for the Printer from the Printer Manufacture is required. Without the Printer driver, the Fonts can't be installed on the printer and used. Years ago, you could install Fonts using different methods like downloading them separately or swapping out a Font Cartridge on the printer, but for the most part, those days are gone. You can check your Printer's documentation, but odds are you will need to use a Windows Print Driver specific to your Printer, and then the Barcodes will show up.
If you are communicating with your printer using a Serial Port (not USB) and there are no Windows Printer Drivers, you may have another option of directly controlling the Printer. That is a pretty huge undertaking though.