Please see my comment to the question. Nobody can see what you are really trying to do. It does not seem to make any sense.
But let's assume for a minute that you really have
chkCources
properly defined and initialized, and the property
disable
really exists and does what it should do. I doubt it, but let's assume it. Even then, look at your line
chkCourses.disable = false; chkCourses.disable = true;
How could it possibly work? If it was enabled, it will state enabled; if it was disables, first statement does nothing.
—SA