The relationship between the ways in which Canadian and U.S. common law and classical Roman law treat blackmail, as d...

"If I threaten to expose a criminal act or embarrassing private information unless I am paid money, I have committed blackmail." Am I mistaken that "unless" should be replaced with "if." Or, we should negate the unless-part for it to make sense that a crime has been committed: "...unless I am NOT paid money, I have committed crime." Please tell me if I am wrong?