Week Number in SharePoint Office 365 Access Application

I'm trying to get the week number in a SharePoint Office 365 Access Application.  I open up the app in Access 2013 and in the query I try using Format([Date],"ww") and I get back ww.  When I use "dddd" or "yyyy" I get back what I expect, the day name or the year but for some reason "ww" doesn't work.  I also tried using DatePart("ww",[Date]) and get an error "The expression you entered uses a function that is not in the valid given context." 

How can I get the week number?

Thanks, Joe