c-sharp : System.InvalidCastException - invalid cast

Hello,
I try to open a blank document from c-sharp exe but it crash on :

unoidl.com.sun.star.frame.XComponentLoader mxCLoader = (unoidl.com.sun.star.frame.XComponentLoader)xDesktop;

with the error :
System.InvalidCastException: can not cast transparent proxy to unoidl.com.sun.star.frame.XComponentLoader

LibreOffice is started with : D:\Software\LibreOfficePortable701\App\libreoffice\program\soffice.exe “-accept=pipe,name=hexa33;urp” .

The object return by xAppFactory.createInstanceWithContext(“com.sun.star.frame.Desktop”, xAppContext); seems not to be empty :
Console.WriteLine(oDesktop) return : Uno object proxy. OID: bb94e48;msci[0];996511b766734d29b4b5b172ab77d0a0

Where is my mistake ?
Thanks.

My program.cs (light):

        unoidl.com.sun.star.uno.XComponentContext mContext = uno.util.Bootstrap.defaultBootstrap_InitialComponentContext();
        unoidl.com.sun.star.bridge.XUnoUrlResolver xUrlResolver = unoidl.com.sun.star.bridge.UnoUrlResolver.create(mContext);
        Object oObject = xUrlResolver.resolve("uno:pipe,name=hexa33;urp;StarOffice.ServiceManager");
        unoidl.com.sun.star.lang.XMultiComponentFactory xMCFactory = (unoidl.com.sun.star.lang.XMultiComponentFactory)oObject;
        unoidl.com.sun.star.beans.XPropertySet xPropertySet= (unoidl.com.sun.star.beans.XPropertySet)xMCFactory;
        uno.Any property = xPropertySet.getPropertyValue("DefaultContext");
        unoidl.com.sun.star.uno.XComponentContext xAppContext = (unoidl.com.sun.star.uno.XComponentContext) property.Value;
        unoidl.com.sun.star.lang.XMultiComponentFactory xAppFactory = xAppContext.getServiceManager();
        Object oDesktop =xAppFactory.createInstanceWithContext("com.sun.star.frame.Desktop", xAppContext);
            Console.WriteLine(oDesktop);
       unoidl.com.sun.star.frame.XComponentLoader mxCLoader = (unoidl.com.sun.star.frame.XComponentLoader)xDesktop;

Hi Astur,
what is the link between the installation folder and my error ?
Can you give an explanation, please ?
Thank you

I resolve the problem:
I add the environnement variable URE_BOOTSTRAP=file:///D:\Software/…/program/fundamental.ini

before starting the exe :
D:\Software…\program\soffice.exe -accept=pipe,name=hexa33;urp;