ValueError: too many values to unpack

[sghignone]

I'm trying to use gff_to_gtf.py to convert Potato genome v.4.03 annotation (http://solanaceae.plantbiology.msu.edu/pgsc_download.shtml; precisely, this file: http://solanaceae.plantbiology.msu.edu/data/PGSC_DM_V403_genes.gff.zip) in gft ,and I'm getting this:

~$ python scripts/GFFtools-GX/gff_to_gtf.py PGSC_DM_V403_genes.gff > PGSC_DM_V403_genes.gtf
Traceback (most recent call last):
File "scripts/GFFtools-GX/gff_to_gtf.py", line 77, in
Transcriptdb = GFFParser.Parse(gff_fname)
File "/home/stefano/scripts/GFFtools-GX/GFFParser.py", line 130, in Parse
ftype, tags = attribute_tags(parts[-1])
File "/home/stefano/scripts/GFFtools-GX/GFFParser.py", line 61, in attribute_tags
key, val = item
ValueError: too many values to unpack

what does it mean?
I just did git clone of the package; am I missing something ?
Thanks
s.

[vipints]

Looking into this.