Plot rendering error: Axes has not been added yet; metadata = {'Entries': 6993178, 'Name': 'InjVcalDiff', 'Overflow': 5084216.0, 'Type': 'Histo2d', 'Underflow': 0.0, 'x': {'AxisTitle': 'InjVcalDiff', 'Bins': 61, 'High': 302.5, 'Low': -2.5}, 'y': {'AxisTitle': 'Occupancy', 'Bins': 49, 'High': 49.5, 'Low': 0.5}, 'z': {'AxisTitle': 'Number of pixels'}}