Did you enter the command by yourself or just copied it into the coomand line? If the latter then please try to type it manually, as I suspect there might be something wrong with the hyphen symbol.
turns out with some more troubleshooting that when I copied and pasted it from the site it used a doube length - in the process. Typed it in manually and it works.
I am now running a full backup with beta 2
Does this mean I can delete all of my old backup files basically?