datepart week not sorting as number

[vmon]

I have graph in a report that show data by week. Problem is the sort is looking at the week as text and not sorting properly. Below is the code. Am I using function wrong or how do I convert "ww" to a number?

(Format([Date],"ww"))

Thanks,
vmon

 

[Rob.Mills]

Change that to DatePart("ww",[Date])