Important: In our general plug-in updates released in November 2012, we have added a workaround for Wavelab 6 and Adobe Premiere so all our plug-ins work again in these hosts. We recommend you to upgrade to the latest plug-in versions.
Background information: Our stereo VST 2 plug-ins with a side chain actually offer 4 inputs: the first two are stereo input, and the second two are the stereo side chain. This works fine in most hosts, but unfortunately Wavelab 6 will not load a plug-in with 4 inputs.
To circumvent this, we offered a separate plug-in version without side chain in the past: Pro-C, Volcano 2 and Timeless 2 still contain this side chain-less version for backwards compatibility. Because the issue has been fixed in Wavelab 7, we decided to drop this special version without side chain in our later plug-ins like Saturn, Pro-G and Pro-DS.
If you must use Wavelab 6 with our older plug-in versions, you can set a registry option to force the side chain to be disabled. First make sure to close your host completely. Click the Start button in the task bar, click 'regedit', Enter. (You may need to give permission to proceed now.) In the Registry Editor that appears, navigate to HKEY_CURRENT_USER\Software\FabFilter\Pro-DS\1.0. (You can of course replace Pro-DS by another plug-in name here.) Right-click, click New, DWORD setting, name it "VST2_DefaultToNoSideChain", and set its value to 1.