Switching symbol sets in PCL5 printers

[William James McEachran]

I'm missing something here.
I've got to print a small string with the "OCR-A" symbol set.
I've got this defined on my print table as

$1b (0O

Nothing happens. No change when the code is encountered.

I then tried using the pre-defined codes for changing the
character sets (print codes 24, 25, 26 in most of the hp print code
tables) and again nothing happened.  The character sets didn't change.

I confirmed that the printer received the print codes (by issuing the
printer command "$1b &s0C $1b Y" -- this causes the commands to be printed
instead of intepreted, cool).  I'm trying this with an all-in-one HP product
which respects all the other PCL5 commands.  I also tried with 'pcl6' and
got the same results.

Question: Beyond issuing the character set command is there an additional
step required to effect the output produced?

Thanks.
-- 
Bill McEachran