Access 2010 SQL Query - Looking up last month's data

Greetings Experts!

I am trying to create a query that looks up dates only from last month. You'll laugh, but here's the where clause I had and it worked:

WHERE (((DatePart("m",[Work week],0))=DatePart("m",Date(),0)-1));

UNTIL January :). I also realized that i wasn't checking the year...

I looked around online, and one answer was to use

DATEDIFF(m,[Work Week],date())=1

But that threw an invalid procedure call error.

All of the other stuff I saw was just wrong like my first attempt :)

As always, your help is greatly appreciated.

Thanks!