Either wiaaut.dll or comdlg32.ocx or which file needs to be registered? I had never heard of wiaaut.dll but VBA says it is the CommonDialog Class; I'm familiar with comdlg32.ocx from prior development.
By the way, both of these are sitting in the ..\Windows\system32 folder which leads me to believe that they are both 64-bit.
I'm already familiar with registering these types of files and just prior to posting this was able to successfully register both of them only to get the same "Class not Registered" message.