Sorry if this is already asked, but I could not find my exact error. I want the image to change as I mouse over and change back as I mouse off. For some reason I get the alert messages, but the actual images do not change.

This is my J script

function altimage(){
                alert("hi");
                document.getelementbyid("header").innerhtml="This is good";
                document.getelementbyid("homeicon").src="homelogoalt.jpg";
            }
            function normimage(){
                alert("bye");
                document.getelementbyid("homeicon").src="Homelogo.jpg";
            }

and this is my div that hold the image I would like to change: