Casting problems when trying to use VCCodeModel

I have been trying to create an Add-In that reads the contents of certain C++ files, in a project. I have had success with previous add-ins in the past and I started to enjoy EnvDTE - but using VCProject - and VCCodeModel - proves a lot more challenging, nothing I try works.

I have typed the code from Microsoft sites identically... example: http://msdn.microsoft.com/en-US/library/ms228770(v=vs.100).aspx

public void test( DTE2 application) 
{
  try            
  {                
    VCCodeModel vcCM = null;                
    VCCodeElement vcCodeElement = null;                
    vcCM = ((VCCodeModel (application.Solution.Item(1).CodeModel));                
    vcCodeElement = ((VCCodeElement) (vcCM.CodeElements.Item(1)));                
    // AddCommentAtStart(vcCodeElement);                
    // AddCommentAtEnd(vcCodeElement);            
  }            
  catch (System.Exception ex)            
  {                
    MessageBox.Show(ex.Message);            
  }
}

I have tried a lot of other examples, nothing I try works - it all fails at the very beginning, at the simplest cast.

So far I have been able to iterate through the ProjectItems and get the .cpp and .h files included, and... what I really would like to do is get a list of #includes from these files. Like http://msdn.microsoft.com/en-us/library/microsoft.visualstudio.vccodemodel.vccodeinclude.aspx... Except it doesn't work...

I have started something like 

public void GetIncludes(ProjectItem projectItem)        
{  try
  {
    FileCodeModel fileCodeModel = projectItem.FileCodeModel;
    CodeElement codeElem = fileCodeModel.CodeElements.Item(1);
    // nothing else would work
  }
  catch (System.Exception ex)
  {
    MessageBox.Show(ex.Message + "\n" + ex.StackTrace.ToString());
  }
}

Please, can somebody help me get something to work ?

Thank you.