PrintTask in ArcGIS Server 10.1 is limitied to 14 items in the Legend

[MiriEshel]

Hi,

We developed an application in Silverlight API 3.1 and ArcGIS Server 10.1 that uses PrintTask from https://utility.arcgisonline.com/arcgis/rest/services/Utilities/PrintingTools/GPServer/Export%20Web%....
Whatever layers are displayed, it always display only 14 items in the Legend, both in "A4 Landscape" and "A4 Portrait" templates.
Is there a way to remove this limitation and show all items in the Legend?

In order to reproduce the problem, I attach the Mainpage.xaml and its code behind. Please build a project with these files, zoom in to the center of the map, check the Activities layer (the first layer in the legend) and also Hospitals and clinics or any other layers you want.
After that, run the ExecuteAsync button and see the result.

Any answer will be appreciated.

Thanks a lot,
Miri