Although this thread is already old (the problem maybe not), I want to reply a solution because I stumbled upon the same problem these days. I am using WaveLab 6 and Waves 9 and got blank GUIs within WaveLab 6 but not within Foobar2000 for example. So, within WaveLab 6 you just have to use XLUTOP Chainer as a step inbetween and load your Waves VSTs within this VST-Chainer. And (maybe) you have to use XLUTOP Shell2VST (once, additionally) to make Chainer recognize the Waves VSTs. Have fun 