Perplexed

[ob1]

Scope is a 10" dob f4.7

I just received my first high-end ep, 13mm Nagler, and caught a break in the clouds to give it a try.  All of my other eps are Orion Sirius plossls.  Conditions were poor, but there were a few stars visible and the moon was viewable, even through the thin clouds passing by.  I was able to bring all of the plossls into focus on the stars and the moon; however, I could not bring the Nagler into focus.  What gives?  What am I missing here?  

If it is a collimation issue, would it not affect all eps? 

[nightfisher]

Did you run out of travel in one or the other direction with the focuser, you may need an extension tube to gain focus with the televue

[ob1]

Did you run out of travel in one or the other direction with the focuser, you may need an extension tube to gain focus with the televue

No, the travel is fine.  It starts to focus, and gets really close, then goes the other way.