Java sample - Failed to open printer ZDesigner ZQ510 (CPCL)

I'm having trouble connecting to the printer via USB using the SDK; but it seems the supplied Java sample does too.

 

In, for example, the Settings Demo; when specifying USB as the communication method the printer appears as 'ZDesigner ZQ510 (CPCL)' and can be selected, but when clicking 'Get Settings' it produces the error "Connection Error! Failed to open printer ZDesigner ZQ510 (CPCL)".

 

I've tried on two Windows 7 machines with the printer installed with the same result. The printer is seen by the computer without any problems and is able to print a test page successfully.

 

Can anyone please advise?