Error fitting Histo from a Canvas

ROOT
4

TFile miofile(“test.root”);
TCanvas can = (TCanvas)miofile.Get(“c1”);
TH1D his = ((TH1D)(can->FindObject(“MCA”)));
Double_t xmin = his->GetBinCenter(1);
Double_t xmax = his->GetBinCenter(his->GetNbinsX());
his->Fit(“gaus”, “”, “”, xmin, xmax);
can->Draw();

TFile miofile(“test.root”);
TCanvas can = (TCanvas)miofile.Get(“c1”);
((TPad *)can->FindObject(“pad1”))->GetListOfPrimitives()->ls();
((TPad *)can->FindObject(“pad1”))->GetListOfPrimitives()->Print();
TH1D his = ((TH1D)(((TPad *)can->FindObject(“pad1”))->GetPrimitive(“MCA”)));
Double_t xmin = his->GetBinCenter(1);
Double_t xmax = his->GetBinCenter(his->GetNbinsX());
his->Fit(“gaus”, “”, “”, xmin, xmax);
can->Draw();