check box enables option buttons but not reverse

I created a function that enables disabled option buttons when a check box is clicked. My problem is that when you click the checkbox again it doesn’t disable the option buttons. I set the options to disabled on page load in the body tag

<!–
function checktrainVal()
{

if(document.forms[0].checkbox6.checked = true)
document.forms[0].training[0].disabled=false;
else
document.forms[0].training[1].disabled=true;

if(document.forms[0].checkbox6.checked = true)
document.forms[0].training[1].disabled=false;
else
document.forms[0].training[0].disabled = true;
}
//–>

Also in #JavaScript _↴