I just tracked some information down on the Microchip website:
Description: Section 5.2 of the datasheet states '1010' is the 4-bit device code.
However, all of the diagrams indicate '1001' is the device code.
Which is it?

Resolution: The paragraph is incorrect.
The device code is '1001' as stated in the diagrams.
I'll give the other code a try!

Rod