This error occurs when you use a version of PS-9000 which is not compatible with the QL-500/550.
Check if the version of PS-9000 is compatible to the QL-500/550 by following the method below.

[Check Method]

1. Check PS-9000 package to see if QL-500/550 is on the list of applicable type or not.
   
   

2. Check the label on the back of PS-9000 to see if "V001" or "R002" is written or not.
   
   

3. Check the version of PS-9000 with WEB browser.
   If the version number is earlier than Ver.1.2.0, then it is not compatible.
   
   

[Solution :
If the version of PS-9000 shows it is not compatible with QL-500/550]

A firmware update is necessary to make PS-9000 compatible with the QL-500/550.
Download the file from the Download page, then update the PS-9000 by following the Manual/readme.