My guess is that BELO has set the criteria so Medina won’t be included based upon this release.
http://www.chron.com/disp/story.mpl/ap/tx/politics/6812368.html
DALLAS A second televised debate between the top two Republican candidates for governor has been scheduled for Jan. 29...........
The News reported that a third Republican gubernatorial candidate, Debra Medina, did not meet Belo’s criteria to be included in the debate.
http://www.belo.com/pressRelease.x2?release=20100112-1954.html
Only poll I'm aware of so far had her at 7%.
Ah, Belo & The Dallas Managed News news(?)paper.