Problem drawing 2D histograms with all entries at zero with colz option

Dear ROOTers,

I'm using the ROOT v5-28-00e. I have a situation similar to the one in the attached file. I have a 2D histogram that is filled with the number returned from another object. If the object is OK, this object returns 0, otherwise, in case of error, it will return a number different from zero, according with an error table. In principle. So, if my histogram is ok , all my entries will be set to zero.

With the past releases I didn't get any error, but now I receive a floating point error and the message

Error in <TGaxis::PaintAxis>: wmin (0.000000) == wmax (0.000000).

Has something changed between the previous release (v5-27-06)? What have I to modify?

Thanks for your help,

Cheers,

Melinda