Audition can find all my VST3 plugins, but none of my older VST plugins

[LoonMaster]

Pretty much what the title says, new to trying out Audition so I might be doing something wrong.
Any .VST3 files it finds no problem, but older VSTs that use the .dll format it just will not pick up on.

I've tried isolating them to their own folders and adding those to the plugin folders in the manager and it just will not see them no matter what I do.

How do I fix this?

[SteveG_AudioMasters_]

Chances are that these are 32-bit VSTs, and they won't work directly with a 64-bis system. You need something like JBridge to enable them to work now (other bridging software may also be available):

JBridge 

The specific reason for suggesting JBridge is that it's known to work.