I think your expected results might be off a little.
With VAAI on, and Fastprovision on... you should see the chain length grow as it is using the VAAI fastclone operations; and VCD is keeping track of the chain. If your storage fully supports VAAI it should still be making "full" vaai clones on your storage solution.
To use VAAI my understanding is you are to turn VAAI on at the datastore - and ALSO turn on FastProvision. Chain length is not a good way to see if something is using linked clones (it should be, but VMware broke with with this VAAI integration) -- A better way is go look on disk, see if you have a -delta file.
Hope that gets going in the right direction - if not working please post back, include the storage vendor in case someone knows of VAAI issues with it.