SetProperty_Float(kXMP_NS_EXIF, "***", ***, 0) wrong behavior

I tested this  on the XMP original samples and had some issue

• Here I just read the data, modify it and then again read it

double xxx;
meta.GetProperty_Float(kXMP_NS_EXIF, "BrightnessValue", &xxx, 0);
cout << xxx << endl;
meta.SetProperty_Float(kXMP_NS_EXIF, "BrightnessValue", 1, 0);
meta.GetProperty_Float(kXMP_NS_EXIF, "BrightnessValue", &xxx, 0);
cout << xxx << endl;

First time it works fine, but when running second time his fails on the first get function with the following error : ERROR: Invalid float string

• Setting the property second time before actually getting it, fixes the issue

double xxx;

meta.SetProperty_Float(kXMP_NS_EXIF, "BrightnessValue", 0.8, 0);
meta.GetProperty_Float(kXMP_NS_EXIF, "BrightnessValue", &xxx, 0);
cout << xxx << endl;
meta.SetProperty_Float(kXMP_NS_EXIF, "BrightnessValue", 1, 0);
meta.GetProperty_Float(kXMP_NS_EXIF, "BrightnessValue", &xxx, 0);
cout << xxx << endl;

       Thought this works, it has no value, as it is meaningless to set a values then get the value that you just set.

Any thoughts ??

Thanks,

Mikayel