why I can't get the date value?

On rails 2.0.2, I debug:
raise @person.inspect
I got:
#<Person id: 102, created_at: "2006-08-16 00:37:50", updated_at:
"2008-01-07 10:46:49", points_count: 0>

raise @person.id.inspect
I got
raise @person.points_count.inspect
I got

but when I use raise@person.created_at.inspect and
I got same error:
You have a nil object when you didn't expect it!
You might have expected an instance of ActiveRecord::Base.
The error occurred while evaluating nil.[]

why? and the date type is different in rails 1.2.6 and 2.0.2?
who can help me? Thanks!

Why are you raise’ing? You can just do puts.

Try puts @person.created_at.inspect