[RWP] Reaper Isn't Seeing All My VSTI Plugs

[Indigo]

    Reaper is only finding some of the plugs in the folder where I'm keeping 
them, the default Steinberg VST plug_ins folder.
I carefully typed in the path to it, in Options Preferences/VST, but Reaper 
still won't list some of the plugs.
Is there a limit on the number of plugs it can display, or can I change any 
default settings in preferences/VST to get Reaper to see that these missing 
plugs are actually there?
I tried some of the plugs in question in Sonar, which listed and played 
them, so I'm sure the missing plugs aren't defective.
Thanks,
Indigo