Error in Invalidating ribbon using Invalidate & Invalidate Control - MS Word 2007 & .Net-4.5.1

I am on .Net version 4.5.1 .

I am creating a MS Word 2007 ribbon control. It's a COM dll. While trying to Invalidate the ribbon or any of the control in there, i am getting the following error related to COM...

m_Ribbon.InvalidateControl(RibbonXTagConstants.gsClassicGroupStatus);

Error:

Unable to cast COM object of type 'System.__ComObject' to interface type 'Microsoft.Office.Core.IRibbonUI'. This operation failed because the QueryInterface call on the COM component for the interface with IID '{000C03A7-0000-0000-C000-000000000046}' failed due to the following error: Error loading type library/DLL. (Exception from HRESULT: 0x80029C4A (TYPE_E_CANTLOADLIBRARY)).

Note that this statement used to work perfectly fine while in .Net version 3.5. I recently upgraded the project to .Net 4.5.1 & started facing this issue. Is there any thing i need to configure or change in .Net4.5.1 . Is there something I am missing?