I have an Ideal plug in gfi/afci tester, I tried to trip a Square D QO arc-fault breaker with it and nothing happened. I tripped the breaker by jumping out the neutral and ground, and it also tripped with the test button on the breaker. Today I tried the tester on a Seimens breaker and it worked. Any ideas?

The only recognized method to test a AFCI breaker is with the built-in test button.

Maybe the Seimens breaker provides class A protection (5ma) and the Square D breaker provides class B (20-40ma).

The Ideal 61-059 & 61-165 AFCI circuit testers have a known issue being that they won’t trip several brands of the new combination AFCI circuit breakers.
Starting this week though, Ideal has released an updated firmware for these testers. If you send your existing AFCI tester to them they will update it for free.
Here is the link from the Ideal website.
http://www.idealindustries.com/media/pdfs/support/notices/afci_breaker_tester_notice.pdf