Acrobat DC Form- Javascript for Multiple Conditional Checkboxes Show/Hide

I have the following code entered at Document-Level Javascript in my Acrobat Form.  "MS CHECK" is hidden my default.  If either "MS CHECK 12" or "MS CHECK 13" is checked, then "MS CHECK" should appear.  The following code works for that part of it, but when "MS CHECK 12" and "MS CHECK 13" are unchecked, "MS CHECK" stays visible when it should go back to being hidden.  Any suggestions?

{

var c1 = getField("MS 12 CHECK");
var c2 = getField("MS 13 CHECK");
var c3 = getField("MS CHECK");

if(c1 != "Off" || c2 != "Off"){
c3.display=display.visible;
} else  {
c3.display=display.hidden;
}


}