I am consuming a cpp COM object from c# code. My c# code looks like this:

try
{
   var res = myComServer.GetSomething();
}
catch (Exception e) { }

However the exception never contains any of the details I set in cpp, in particular my error message.

In my cpp side I have followed several examples I have found on the web:

...
ICreateErrorInfo *pcerrinfo;    
IErrorInfo *perrinfo;    
HRESULT hr;    
hr = CreateErrorInfo(&pcerrinfo);    
pcerrinfo->SetDescription(L"C++ Exception");    
hr = pcerrinfo->QueryInterface(IID_IErrorInfo, (LPVOID FAR*) &perrinfo);  
if (SUCCEEDED(hr))    
{  
  SetErrorInfo(0, perrinfo);  
  perrinfo->Release();    
}  

pcerrinfo->Release();    
return E_FAIL;  // E_FAIL or other appropriate failure code  
...

Am I missing anything? Is there anything else that could affect this, like marshaling, the interop creation or attributes of the com server itself?