First, I moved your post in the correct section, which is FSX JFK.
If the installer says you don't have Acceleration or SP2, then you don't have it.
To check your version, go into your FSX folder, right-click the FSX.EXE file, select "Properites", then "Details". The file version should be 10.0.6.61637.0 for Acceleration, or 10.0.61472.0 for SP2.
FSX RTM is 10.0.60905.0 and FSX SP1 is 10.0.61355.
If your FSX.EXE is not the correct version, It's possible your Acceleration install has failed somehow, or you ended up with mixed files, which can lead to all sort of problems.
Not a problem of our installer, of course. In fact, by refusing to install on an unsupported version, or a version with mixed files, it will prompt you fixing your problem first.