JavaScript If Statements Aren't Working For Me, It won't work

I need help with my code. I have tried to make a code but this won't work. could someone please try to help. I can't tell what it is!

if (document.getElementById("killer").style.marginLeft > document.getElementById("player").style.marginLeft) {
        alert("1");
    };
    if (document.getElementById("killer").style.marginLeft < document.getElementById("player").style.marginLeft) {
        alert("2");
    };

please help me!