Hi again,
I've checked for Aitken on the 1841(mistake should be 1851) but no joy so far I'm afraid.
Freecen is a great free to use site but unfortunately not all Census data is transcribed for all areas.
The site as you can read on it's home page has been set up, updated and maintained by volunteers who transcribe from original Census books.
Only about half of 1851 Census for Perthshire is online

at the moment.
Keep trying with different version of spellings for Aitken and Steele/Steel/Steal/Stiel on Scotlands People and maybe you'll find him.
Good luck with your search,
Looby
