Problem with TH2:Add


I was trying out a piece of code that worked before in an older version
of root but no longer does. When it attempts to subtract one TH2F from another the result is always empty.

The demonstration code attached reproduces the problem.
As it is the histogram produced is empty - if I uncomment the
commented line then strangely it works.
I am using ROOT 4.00/08 (the same thing happens in 3.10)
Does someone know the reason for my problem?


Test.C (651 Bytes)

TH2 are not drawn if the number of entries is null.
Either use AddBinContent instead of SetBinContent
or add the line