Hi Rut Margalit,
The current official Moonlight version is for Silverlight 2, although it also introduces some Silverlight 3 features. Our current offering for Silverlight is built on Silverlight 3. Therefore, there might be some problems when running our controls on Moonlight. We are working in this direction to provide full support for Moonlight for Silverlight 3 once it goes official.
the Telerik team