The Liberal motion adds the new offence of “attempt”—thank you, Ms. Sahota—because in the Criminal Code there is a general provision that applies to other offences in the Criminal Code. It is an offence to “attempt” to commit an offence under the Criminal Code.
Of course, that Criminal Code provision does not apply to other federal legislation. That's why the government recommends adding the offence of “attempt” to cover a bit wider.