This is a known issue with Silverlight 5 printing on postscript printers. Usually, it can be solved by installing the latest postscript divers on your printer. If this do not help, you can set the ForceVector property to false in order to have Silverlight properly fall back to the "old" bitmap printing that should work.
Hope this information will help you to solve this issue. If you have further problems do not hesitate to contact us.
the Telerik team