Sorting by Month Number

[Gorio]

I am trying to create a report that breaks down by months. However the sort order is incorrect. In the query I created:
MonthNum: Format([DISDATE],"m")
But the report sorts in the following manner: 1, 11, 12, 2, 3, 4 .....
How can I make it sort 1, 2, 3, 4, ....?

 

[Gorio]

Thanks for the help. I'm looking forward to putting it in place.