WARNING ymin must in but the bounding boxes are fine


I have a custom dataset prepared in PASCAL format and when i am trying to load the dataset appear a warning message which says there is some error with the label in the image img_76_FliplrFlipud_1387.xml.
This is the information of the imagen from the label .xml.

To sump up, the image has this dimensionality 1648x524 and i think this warning appear because, i have somes ymin == 0

There is something wrong here?