It would appear you are trying to use the old dll with the new resources. You can either, reinstall the v2.1 Z3TA+2 from your account https://www.cakewalk.com/My-Account/Products to get the old resources or reinstall the new v2.2 to use the new resources. If it were my machine and I wanted to install the new version, I would move the folder containing the old dll out of the VST scan path first just to make sure or run the uninstall from the Windows control panel.

Snehankur
NOW?

 
What version is displayed in Stand Alone  (which works) ?
 
When and how did you install your current version of z3ta+2 ?
 
The lastest version is 2.2.1.114 that you might install.  This version may have some problems with old projects using z3ta+2 presets - for which a version 2.2.2 is on its way.
 

Thank you Paul
Thank you Scook
 
I have uninstalled and reinstalled. Now its working fine.
It didn't give me option to select my VST drive to as installation destination. Installed in C:\progfile\cakewalk\z3ta...
Then created a folder in the VST Drive, copied the .dlls, run manual vst scan and got added in the Instrument list.
 
Regards
Snehankur
 

 
It might be a good idea to update z3ta+2's path information in the Windows registry, under
 
HKEY_LOCAL_MACHINE / SOFTWARE / Cakewalk Music Software / z3ta+ / 2.0 /

 
I just noticed that Z3TA+2 is usuallly spelled with a space, ie. "Z3TA+_2" (no underline) in case your folders are like mine.  It's not terribly obvious.