Observed 6.000000 events in bin 3 with zero event yield

Dear experts.

I am doing a very simple fitting. From the fitting log, I could see some good information like:
RooFitResult: minimized FCN value: 7.85754442757693, estimated distance to minimum: 0.000301988115828802
covariance matrix quality: Full, accurate covariance matrix
Status : MINIMIZE=-1 MINIMIZE=0 MINIMIZE=-1 MINIMIZE=0

But the fitted error of the parameters are very small like:
ATLAS_norm_Wl 8.2010e-01 +/- 8.30e-07
ATLAS_norm_Zl 7.9477e-01 +/- 8.26e-07

Any one has an idea ?

From the log file, I see some errors like:
Observed 6.000000 events in bin 3 with zero event yield

The histograms that I am using are just having 2 bins. what would the bin-3 come from ?

The log file and the workspace are attached.

Thanks!
Javier
Test.root (47 KB)
log.txt (26 KB)

Hi,
Can you please post also the fitting code ? I have tried fitting the simPdf in your workspace with the corresponding observed data and I did not notice this problem

Lorenzo

Dear Lorenzo

I debugged for a while and figured out the issue from my part.

Thanks!
Javier