OpenOffice Bootstrap error in C#

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C#

C#4.0

I'm trying to implement openoffice in my C# program,I'm getting an error
my code is:

XComponentContext comp = uno.util.Bootstrap.bootstrap() ; //here is the error

           XMultiComponentFactory xmcf = comp.getServiceManager();

           Object orawdesk = xmcf.createInstanceWithContext("com.sun.star.frame.Desktop", comp);

           XDesktop xdesk = (XDesktop)orawdesk;

           XComponentLoader xcomploader = (XComponentLoader)xdesk;

Error is:Unable to cast object of type 'System.IntPtr' to type 'System.Runtime.InteropServices.GCHandle'.

How can I resolve this error?

Thanks!