From the JV16 FAQ:
Question:
Are your products compatible with Vista?
Answer:
All of our products are compatible with Windows Vista but only with the normal 32b versions, not with the x64 ones.
So it is offically not supported.
That's why I haven't been able to use JV16 for the last 14 months. Back then I was under the impression JV16 would be 64 bit compatible soon. But it seems it is not that simple.