Scaffold option -r error

[arif-tanmoy]

Hi,
I tried to use the -r option to increase gap-size. However, getting the following error. Any idea how to resolve this?

$ ragtag.py scaffold Ref.fasta Assmebly/sample_contigs.fasta -o RagTag/ -r 150
usage: ragtag.py scaffold <reference.fa> <query.fa>
ragtag_scaffold.py: error: unrecognized arguments: 150