I would like to delineate watershed for polygons which represent lakes. However, I received an error which is attached below. From the information which I found in the forum I should change in my attribute table values -1 to 0. I did this; however, it did not change anything, I am still occurring the same error. Is there some way to solve this error? Or maybe another approach which can be used to delineate watershed for polygons? Thank you in advance for help.