My AutoCAD does not recognize the PDFATTACH command.

If AutoCAD 2009 reports PDFATTACH, PDFLAYERS, PDFCLIP or PDFADJUST as unknown commands, you have probably not installed the Bonus Pack 2.

These commands are included in the "Subscription Bonus Pack 2", not in the basic version of AutoCAD 2009.

Download and install the Bonus Pack 2 from your Subscription Center.