That's odd.
Can you try creating a brand new project from scratch, then adding a connection and a package. Create a script task in your package. The reference mentioned above should be in the script task, by default. Compare this with what you have now to see whether it gives you any clues.
If you haven't even tried to resolve your issue, please don't expect the hard-working volunteers here to waste their time providing links to answers which you could easily have found yourself.