(--username) Can't figure it out

I have tried to find an example of this being used but can't seem to track one down.

This is how the hash looks.

username,4738473842894985 in /root/test.txt (hash example is me hitting random keys)

My input is all kinds of variations of this

cudahashcat -m 0 --username /root/test.txt /root/rockyou.txt -o /root/pleasehelpme.txt

I have moved the --username all over the place and just get No Hashes found and length errors.

What am I doing wrong?