[ROOT] GetConfidenceIntervals with TMinuit?

Hi,

I want to use the GetConfidenceIntervals function using TMinuit.
Below is a short example of what I'm trying to do.
I know where is my error, but i don't know how to get it work.
Is it possible to obtain the confidence interval with TMinuit?
Do I have to compute it manually?

Thanks,
Martin

--------------------

TMinuit* minuit = new TMinuit;
minuit->SetFCN(&Chi2);
...
minuit->Migrad();

TGraph gConf = new TGraph(50);  // the graph which holds the contours
TVirtualFitter* tvf = minuit->GetFitter(); //This doesn't compile...
tvf->GetConfidenceIntervals(gConf,0.95);   // 95% confidence interval

//Instead of the 3 lines above I also try the following but I get a 
//Break - Segmentation when running.
TVirtualFitter* tvf = TVirtualFitter::GetFitter();
TGraph gConf = new TGraph(50);
(TVirtualFitter::GetFitter())->GetConfidenceIntervals(gConf,0.95);