--not all physicians/facilities find the Igenex tests valid, even when their results match CDC critieria, and not all sources agree on what should be the CDC criteria.

Much of the controversy stems from which of the "bands" that show in the test are definitely the result of the Lyme organism and which may also be associated with other tick-borne organisms--and whether these bands' presence/absence may change depending on the timing/progression of the infection . . .

There's been a lot written on this, but these are among the most comprehensive summaries:

http://www.canlyme.com/flawedtest.html

http://www.mdlab.com/pdf/lyme_disease_testing.pdf

http://www.fda.gov/medbull/summer99/Lyme.html