That assembly does not allow partially trusted callers When Using AutoCompleteBox in DataGridTemplateColumn

I Develope a XBAP Partial trust that use datagrid. This DataGrid has a TemplateColumn that use AutoComplateBox as Editing Element. When Click on One of that Column's cell throw the exception

System.Security.SecurityException: That assembly does not allow partially trusted callers.

any idea? tanx

This problem solved in Visual Studio 2010 and can use it without any exception