453.4875 is the right frequency for Hermitage. I can also verify activity on 460.4000 but it must be a bit too weak for me, since all I got was semi-garbled audio. There's also some analog FM on there too but it was too weak to make out as well.
If you're getting good data on the New Castle frequency, you should stick around on it for a while. It's pretty active during the day so you should hear some audio in fairly short order. You can use that to tweak the inlvl% setting, and as proof that it's set up right. I'm not sure who all uses that system as some of the talkgroup ID numbers I've seen aren't yet listed in RR. You should eventually hear Noga Ambulance though.
If you have your radio scanning, you might try letting it just sit on the Hermitage freq. DSD might lock quicker that way. Just a thought. Other than that, I'd be looking closely at the tap.
Just for my education, what kind of radio are you using?
Edit:
Oops. I just noticed you said it was a Pro-2006 scanner. Guess I should read all the way to the end.
I found this webpage after a quick search:
http://ukradioscanning.com/viewtopic.php?f=19&t=179
It shows 3 different ways to tap a Pro-2006. "Version 2" mentioned something about the discriminator output having a small IF compononent that needs filtering out, so that could possibly be an issue.
Edit #2:
I guess I should read back some too. I have an older slower laptop, and it still spits out audio when DSD tells it to, but the audio is completely distorted and unintelligable. It basically cuts out when the processor goes around 100% usage (which is all the time). What I'm trying to say is it should still spit out some kind of garbled audio, even if it's too slow. I could be wrong about that though. How fast is your computer? Dual core works best, but my 1.3gHz Celeron will still spit out garble.
I went and got my HAM license a while back mostly just to prove to myself that I could do it. Unfortunately relative poverty has kept me from buying a rig and getting on the air, so I'm relegated to the listening portion of the hobby for now.