It's a good question. Note that on the PTSC website the following licensees are also missing from the list:

http://www.ptsc.com/corporate/index.asp

Agilent

Bull

American Power Conversion

WMS Gaming

Verigy

Matsushita

Toshiba

NEC Electronics America (the previous NEC is listed but not the recent settlement)

Based on what I consider to be the below average quality of PTSC's website with respect to their use of it in informing investors in a timely fashion (many spots where the information is not current by a long shot), it could be that whoever maintains the site is to blame. Maybe they just screwed up. lol