homemade helper isn't working

[eluser]hht1230[/eluser]
I have functions that are used in several parts of the site to format strings so I thought I would put them in a helper. I created myformat_helper.php with those functions in system/application/helpers and in the controller I do $this->load->helper('myformat') but I get a "Call to undefined function" in the view when I try to call any of the functions. It works fine when the functions from the helper are physically in the view page, so I must not be accessing the helper correctly. Some dumb thing I have overlooked?

Also, why is there no closing ?> in the built-in helper files?