Erase Byte range feature not working for torrent

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After there was a crash which made Shareaza think somehow that most of a torrent I was downloading had already been transferred, I tried to manually erase a byte range of that torrent and I always got an error message...
EDIT: I'd like to add that at the time I took these 2 pictures, more than the first 10% of the torrent had completed downloading, so when deleting that range, its starting point was clearly within the part that had already bee downloaded.
pic2
After there was a crash which made Shareaza think somehow that most of a torrent I was downloading had already been transferred, I tried to manually erase a byte range of that torrent and I always got an error message...
EDIT: I'd like to add that at the time I took these 2 pictures, more than the first 10% of the torrent had completed downloading, so when deleting that range, its starting point was clearly within the part that had already bee downloaded.