SCT and Barlows?

I just spent my first evening with my new (pre-owned) Celestron 9.25" SCT under a beautiful Milkyway at the DAS darksky site outside of Denver. One thing I quickly learned is that my Meade 2-3X barlow don't work too dang good with this scope. I cannot bring my TV 15 and 20mm occulars to focus. Can someone tell me what's up and what I need to look for in a barlow?