Sqlmap isn't doing what i want him to

i'm using:

sqlmap -u "http://website.com" --data="cmd=register&user=test&pass=test&mail=example@test.com" -p mail,remote_addr --headers="REMOTE_ADDR:1" --randomize=mail

What i want to do?

I want sqlmap to test just the remote_addr and the mail param using a randomize value every time.

Thanks!