Ive been using sonar 8.5 producer with no hassle since 2010, I have an issue with Dimension Pro, sounds are not loading ? Not sure what to check for ..Could I possibly be running out of RAM. I do have 16 GB 
 

Try listing your system specs and a step-by-step of what you are trying to do.  Any error messages or pics would also be helpful.

Thanks for that . I am using Windows 7. i7 proccesor,16 gb ram...Sonar Producer 8.5
I have inserted a midi track for a Bass Part..Then on that track I have clicked on Insert soft synths , and selected Dimension  Pro , then gone into dimension Pro and selected a Fingered bass from the real bass selection,
When i tried it again just before it finds the bass sound all ok , when i try to play that bass in a recording session with an existing drum track and audio guide. I can hear the bass , but its is there and it can be heard in the play back ..
In saying that if I open another existing project with a bass line No Problems I can re record , all is ok . Sorry I am finding it hard to explain hat the problem is I am not very Audio/Midi Savvy
 

Just went in a gain , the problem is , Even though I have highlighted the bass track, when i play the midi keyboard (during record only) it is playing the drum sounds from another track , when I stop recording and listen back , the new bass line is there. weird