Trying to create a bootable usb for Mavericks

I got this message after I went through the sudo command and entered my pw. I just need to know if I have to start over because of the “Invalid argument”

dd: /dev/rdisk1: Invalid argument 936+1 records in 936+0 records out 981467136 bytes transferred in 125.873935 secs (7797223 bytes/sec)