Please make sure you have installed the correct version of UVI Workstation (32-bit or 64-bit) that matches the architecture of your favorite DAW/sequencer/host.
For instance, if you are running with, let's say, Ableton Live 64-bit, you have to install the 64-bit version of UVI Workstation.
Then please make sure that your DAW is pointing to the correct plug-in folder. You may need to use the Rescan option from the plugin manager of your DAW.
If you have any trouble, please contact our Support Team.