Depends on where and how you installed stuff.

V4 has an expandable CR2.  That means it loads other scripts that load other scripts.  When you buy A4, it adds new scripts to the Runtime/Libraries/!DAZ folder.  There are BAT files that run a program that scans for these new scripts and adds them to the loader that the CR2 calls.  These scripts contain the empty dials that the INJ files need to put the deltas into.

Dispite what the installer says, you don't have to load them in the poser main folder.  But you do need to install them all to the same runtime, be it the internal one for poser or an external one.  All the V4 figs need to install to the same runtime.  That includes V4, G4, A4, and S4 as well as NPM and NBM.  Then you run the bat file that rebuilds the loader script after each install. 

It will NOT work if you install V4 to one runtime and A4 to a different runtime.

I use Poser Pro 2010 and I have a runtime specifically for the Gen4 figures (V4, M4, etc).  All of my V4 addons (V4, G4, A4, S4, NPM, NBM, NGM, etc) are installed to it.  I NEVER install anything to my poser application folder.  V4 runs just fine for me as do all her mutations.