Another way to do this:
Add an ID to the <select>, in addition to the name.
And then you can always find it using
ID's must be unique, of coruse, but I don't think that's a problem in this case, is it?
Just give the <select> the same ID as its name: lisSeason
So in place of
intSeasonIndex = document.forms("frmAdminFixtures").Elements("lisSeason").SelectedIndex + 1
you would just do
intSeasonIndex = document.getElementById("lisSeason").SelectedIndex + 1