Did you enable the print handler in agent configuraiton? Also you have to add printer into managed category prior to enabling the rule.
Unfortunately, not all printer drivers are compatible with HDLP. From ePO, you can run a query called "Unsupported printers". If your printer shows up in the resulting report, then its driver is not compatible. As I recall, a driver needs to be able to accept the "RAW" format from HDLP in order for it to be compatible.