This is not an expected response in the described situation.
Did you install Service Pack 2 directly to this VM, or was the SP 2 slipstreamed into the installation media.
My inclination is that the installation of SP2 is not complete, and it's resulting in a failure to properly detect the presence of the service pack.
If possible, I would recommend RE-installing Service Pack 2 and then retrying the Extension Pack installation.
If that does not resolve the issue, please send an email to email@example.com with your availability and we'll set up a GoToMeeting session with a support tech.