An attempt to commit a crime is an offence, whereas an attempt to commit a crime under a provincial statute is not technically an offence. And it is not hard to understand why that is the case. In fact, the criminal provisions of provincial statutes cover all sorts of things. Are you going to punish someone for an attempt at speeding which did not succeed? It covers all kinds of minor things. It also covers more major offences.
However, in this case, lawmakers did not feel it was appropriate to make this a crime, whereas under the Criminal Code, any attempt to commit a crime is a crime.