Adding Thirdparty control in WPF

We have used C1DateEdit control(Component one Control) in WPF application and it has some issue with it.
Please find below the scenario and the issue.

Scenario 1:
Step 1 : Create a WPF-Windows application and add Window1.xaml .
Step 2 : Add C1DateEdit control in WindowsFormsHost element.
Step 3 : Execute the application.
Step 4 : Click on the dropdown of the DateEditControl. It throws the below exception.


Scenario2:
Step 1 : Create a WPF-Windows application and add Window1.xaml .
Step2: Create a usercontrol(ucDateTimePicker.cs) by adding C1DateEdit control in a panel and set panel to fill the usercontrol.
Step3: Add the user control in WindowsFormsHost element of Window1.xaml.
Step 4 : Execute the application.
Step 5 : Click on the dropdown of the DateEditControl. It throws the below exception.

Expected Result:
When click on the dropdown of the DateEditControl, it should drop the calendar.

Exception:
System.NullReferenceException: Object reference not set to an instance of an object.
at C1.Win.C1Input.C1DropDownControl.OpenDropDown()
at C1.Win.C1Input.C1DropDownControl.a()
at C1.Win.C1Input.C1DropDownControl.WndProc(Message& m)
at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)

Note: The same scenario works well with Windows application of visual studio 2005.

Thanks
Raje