Printing to scale

I'm a newbie at Flex. I have created a flex 3.2 map using the Application Builder and I'm using the print widget with the Print with ArcGIS Server option. If a user enters 1200 on the scale so the map will print at 1"=100', it's not printing at that scale at all. Any ideas as to why? I work for a water utility and it's important that users can print to scale.
thanks
Karen