If you take a look at this:

https://cdn.pinnaclesys.com/SupportFiles/Hardware_Installer/readmeHW10.htm

you can see a number of Dazzle devices that never had 64 bit drivers written for them. If your "old" device is one for those, it won't run under PS26/64bit.

Incidentally, there are some 64 bit drivers for "movieboards" and the like, but these are bugged and don't run if you have 2GB or more of RAM.

So you need the current device, ot to pick up a USB 500/510/700/710 on ebay. However, the value of the compatible older devices seems to be known, so a new Dazzle is probbaly the cheapest option.