If you're trying to apply CS5.5 updater to your CS5, it won't work; they'll only update an installed version of CS5.5.
Ah, ok. Thanks.
Sorry, I could have been a little more helpful.
If you want to upgrade (not update) from CS5 to CS5.5, you'll have to buy a CS5.5 upgrade.
You can purchase it from Adobe here:
Look at the box on the top right that says "InDesign CS5.5" and below that "Upgrade from US $119.00"
And that won’t work if you have a suite.