By default, the Code Inspection feature of Visual Assist is not active in 3rd-party directories. You can change the behavior, i.e. make the feature active in the directories, by setting the following registry key:
HKCU\Software\Whole Tomato\Visual Assist X\<IDE spec>\Code Inspections\Exclude3rdPartyDirectories = 00
Restore the default behavior by setting the value to 01.