You can't see the VC of few planes, or all the VC's of all the planes that should have them? :-?
If you can't see ANY VC of ANY PLANE (not even the default) go in the fs9.cfg and search the string SEE_SELF= under the [GRAPHICS] tab and ensure its value is 1 (if it is 0, among other things, you'll never be able to use any VC).
If you can't see
only some VC of
only some add-ons, then probably those add-ons are published in different versions, like with VC version and without VC version, like in the case of the Aero Commander, and you mistakenly downloaded the NO-VC version.
Ensure, in this case, that you have downloaded the correct version of the plane.

There's but one real cure for human stupidity. It's called DEATH.
At the moment mourning the assassination of sarcasm and irony for the good of the "higher".
Proud FSIX user. Active user of FS98, X-plane and novic