Excel WPF Addin Drag Drop Error

I created a Sidebar in Excel using WPF, and trying to drag some some objects from the WPF Pane to the spreadsheet. The Application object in WPF is null. Please guide me how to Achieve this Drag-Drop s开发者_StackOverflow社区imple text from WPF Excel Addin to The spreadsheet.

Thanks in Advance

The answer for this problem is well explained in MSDN article section "Hosting WPF Content in a Microsoft Win32 Window"

This will be for any one who wants to get the power of WPF to build excel addins.