5" refractor

I've seen a lot of discussion of the Orion 102, etc, but was wondering if I'm the only one that has purchased the 5" from Apogee. It's my first scope, and I don't have much in the way of previous experinence with other refractors. I like the 1200, f/9.4, but was wondering this: I wasn't able to get a focus on Jupiter (this eve) with a Celestron 10mm and a barlow. Do you think this is an eyepiece issue, or a telescope optic issue? btw, I have used a 6mm Orion Expanse in it, and wish I hadn't sold it.