Help With CreateNewObjectExQuick Method

I am creating a workflow and part of it is a script that would duplicate the document object.  So far it is working, but I also wanted to change the permission of the new (duplicated) document object.

I am using the CreateNewObjectExQuick Method and accoridng to this reference: CreateNewObjectExQuick Method, the Access Control List parameter should have what I am looking for.

If I leave it as 'Nonhing,' then the new document object uses the default - or inherits the NACL of the Class where it is in.  

If I set it to '46' which is the NACL ID that I want to set the permission of the new/duplicated document to, then I get a 'Type Mismatch error'

Please advise.  thanks.