AvalonEdit autocompletion didnt work as expected

i have a strange effect in the avalonedit control. i use the following code to add the common .net assemblies(mscorlib, System and so on) and an external library(NetOffice)

IProjectContent result = _contentRegistry.GetProjectContentForReference(assemblyName, assemblyLocation);
_projectContent.ReferencedContents.Add(result);

now use the control at runtime and type the follwing code in a class method(syntax is okay for the whole textfile)

NetOffice.ExcelApi.Application app = new NetOffice.ExcelApi.Application();
int i = app.Caller.GetHashCode();

the Caller property is System.Object but didnt see the intellisense here(the 4 wellknown mehthods). all other completion things works fine! i do something wrong or may the reason is because NetOffice is bit a strange in class definitions. this is -a part- of the NetOffice.ExcelApi.Application definition:

public class Appication : Application
{
  //..
}

public class _Application : _Application_
{
    public object Caller { get;}
}

public class _Application_ : COMObject
{
    public object Caller(object index);
    public object get_Caller(object index); 
}

is it possible this strange definition cause problems or i do something wrong?

*thanks for clearification
Sebastian