Rectangular DataMatrix not printing


I'm trying to print a label with a rectangular data matrix by passing zpl to the printer. It works OK when trying to print a square one but doesn't work when its a rectangle.
The printer firmware is V53.17.7Z so should be new enough to support rectangular codes.
The ZPL is:
^FT192,32^A0R,17,16^FH\^FDYYWW Serial^FS
Thanks for your help