Studio instrument problem

I'm confused by what you're actually doing.  remember we can't see what you see, so give us as much of the detail as you can.

when you say you are setting the output of the track to the selected studio instrument - what exactly do you mean by that?  are you changing OUTPUT, CHANNEL, BANK and PATCH properties on a MIDI track?  or did you insert a SIMPLE INSTRUMENT TRACK?

and when you say "and no sound is hear" - exactly what are you expecting at this point?  no sound will be heard until you play the project, or audition some MIDI loops, or click on one of the kit pieces.  you didn't say what you were doing to not hear the sound at that point.

if you press play and select a different drum kit, sound comes through - but once you stop the track no sound comes through - are you saying that once you stop the playback you can click on a kit piece and no sound is heard?  or what?  how are you trying to trigger any sounds after playback has stopped?

that's better information

when you first load SI drum kit, it does not have a drum kit loaded automatically, you have to load one, so the reason it won't play until you load an "alternate" kit is because there's not a kit really there to use until you load one.

however, there may still be problems with your description of your MIDI track.  you didn't really answer if you are changing the parameters of OUTPUT, CHANNEL, BANK & PATCH on a MIDI track or if you have a simple instrument track inserted.  I'm suspecting that what you're having a problem with that it doesn't play after you've stopped the playback has to do with changing the output and whether or not you're doing all of it correctly in a simple instrument track or MIDI track.

are you using a MIDI and OUTPUT track combination or are you using a SIMPLE INSTRUMENT TRACK?

what are the parameters on the track(s) set to exactly?

Hey Beagle or anyone who can help.I'm having a very similar situation over here.But still no fix.I'm using sonar 7,and native instruments.
And using a MIDI and OUTPUT track combination.
 I'm trying to add in a bass track with the SI-bass.The usual way.insert soft synth.SS options midi source synth track folder first synth and enable midi output all checked.I've tried with out the midi checked.But still I get no sound from the bass.I can click the string and let it ring out,change a setting on the midi track and the sound will magically be there,but only if I don't touch any other controls.
 It also runs perfectly as a stand alone.ONly issues once I try to bring it up in Sonar.
 I've also noticed in the soft synth options ,as I said,the instrument will play once I have the options menu open,but  as I try to enable to midi output and click ok,it never stays enabled.
Ive recorded before with the si-bass with no problems until now.Any help would be hugely appreciated.