Slider moves wrong way?

Slider moves wrong way?

I tried the vertical slider example, with slight modification, the test file is: http://ancestry.bagnall.co.uk/time_machine/test.asp . I find in FF that when clicking on the slide, the button moves in the opposite direction. And I also can't click and the slider. I must have made a fundamental error, but I can't spot what it is. Can anyone help please?