Well as far as I have been reading you may want to check and see if he meets the dependant:
Dependent children : Refers to the children of the applicant or those of the spouse or common-law partner.
They must be:
under the age of 19 and not have a spouse or common-law partner, or
---19 years of age or older and unable to be financially self-sufficient since before the age of 19 due to a physical or mental condition.
Definitions of Dependent children (Types 1 and 2)
Your child or the child of your spouse or common-law partner can be considered a dependent child if that child meets the requirements of type 1 or 2 below:
TYPE 1
The child is under the age of 19 and is single (not married and not in a common-law relationship).
TYPE 2
The child is 19 years of age or older and has been financially dependent on a parent since before the age of 19 due to a physical or mental condition.
Note: The above requirements must be met on the day the Case Processing Centre receives a complete application. Whether or not they have attained the age of 19, children falling under type 1 must not be married or be involved in a common-law relationship at the time of visa issuance and when they enter Canada.
As per Guide 5772 Definition of a dependant. go to CIC.