On page 291 of ZPL manual you can find description for ^PA command that you may need to use for bidirectional printing. This command is available only for printers with firmware version V60.14.x, V50.14.x, or later:
You may need to check your printer firmware version.
In case you have no information on your printer firmware version you can read it from printer with following command:
! U1 getvar "appl.name"
Software Engineer, Kutir Mobility
Posted on behalf of Zebra Technologies