Invalid Cast Exception creating PropertyManagerPage in C#

Hello, I am using the SolidWorks 2007. I try to create a newPropertyManagerPage in C# but on having executed the code methere appears the exception InvalidCastException i I do not findthe reason.

m_Page =(PropertyManagerPage2)swApp.CreatePropertyManagerPage(title,buttonTypes, pageHdlr, ref errors);

The code of my application I have adapted it of the same example inVB of the page of solidworks.
would someone be able help me like? I attach the code in a VisualStudio project

thank you in advance