Rle_encoded_masks -> labels

I am working with rle-encoded masks. There is just -1 if there is no mask and a string containing an rle encoded mask if there are annotations.

But I do not have any labels to the masks. If I try to create a databunch from the data I get the error:

Exception: Your data isn't labeled, can't turn it into aDataBunchyet!

Why do I need labels?

This is how I try to create my databunch:

src = (SegmentationItemList
        .from_csv(path_jpgs, 'train-rle-sample.csv', header=None, convert_mode='grey')

data = (src