Can anyone tell me what the proper folder location to install VSTi's and plugins is?
You might have 2 options when installing....let the program choose it's basic install folder and then when it asks for the vstplugins folder you should probably decide on one and install all vst2 to that folder (but multiple folders still works)
For 64bit this could be program files\vstplugins or program files\Steinberg\vstplugins but could be anywhere you choose. The important thing is you know where it is/they are and in plugin information this path/s is/are listed under the vst2 plugin folders tab.
If this is all correct and you still don't see the plug, from the start menu open Steinberg\Cubase (your version)\User settings data folder and check the VST2xBlacklist Cubase.xml (open with a text editor like notebook)
If it's listed, delete this xml completely and start Cubase again and it will try to scan again..if it keeps adding the plug to the blacklist there is a problem with compatibility.....are you using latest updates, is it 64bit compatible??
i7 email@example.com, 12Gb, W7HP x64, Cubase 7.5.20 x64, Steinberg UR28M, Alphatrack, Wavelab Elements 7.2.1.