what exact version of Ae do you have? and what exact Quicktime version? and what exact Os version?
also show us the message you are getting
Version 12 of Ae
Newest version of quicktime
After Effects error: file 'file.mov' cannot be imported - this '.mov' file is damaged or unsupported.
there were problems with QT files in 12.0. you should be using 12.2.1. make sure this is the version number appearing when you launch Ae. you can also find it in help->about After effects. make sure your QT is 7.7.9.
How do I update my AE?
Through the Creative Cloud Desktop App.