You can't sponsor if
"(i.1) an indictable offence involving the use of violence and punishable by a maximum term of imprisonment of at least 10 years, or an attempt to commit such an offence, against any person"
Robbery probably falls under this.
You will need to have either:
(a) on the basis of a conviction in Canada in respect of which a
pardon has been granted and has not ceased to have effect or been revoked under the
Criminal Records Act, or in respect of which there has been a final determination of an acquittal; or
(b) if a period of
five years or more has elapsed since the completion of the sentence imposed for an offence in Canada