No error bar after a fit using ROOT6

Dear Rooters,
I have a little problem when drawing the results of a fit with ROOT v6-02/28.

Basicaly, I want to fit a 2D model RooAddPdf to a 2D data RooDataHist using extended likelihood with the fitTo() method. For more precision my model has 2 input correlated parameters and 2 output observables. I’ve created a binning of the input parameters (around 200 combinations of the 2 input parameters) to generate RooDataHist with my model. I then use this set of RooDataHist to build the RooAddPdf that I fit to the data.

My problem is linked to the ROOT version I am using. The fit seems to be done correctly using ROOT v5-34/28 and v6.02/08 and gives the same results. Nonetheless when I draw the results of the fit I have no error bar with ROOT v6.02/08 when I have using the exactly same code with ROOT v5.34/28.

NB: I’ve noticed another problem when saving the RooAddPdf or my RooWorkspace in a “.root” file with the method: “SaveAs(”./out.root")" that works fine with v5.34/28 but returns a nice “*** break *** segmentation violation” with v6.02/28.

Does someone have any similar problem ?

I’ve added in attachment an example of the result of the fit with ROOT v5.34/28. The blue lines corresponding to the fit result and the points to the data.

example_fitresult_obs1&obs2.pdf (23.7 KB)


In order to investigate this problem, can you please attach the workspace and the code reproducing it ?

Best Regards