[jQuery] Interface Elements problem!

[mumf83]

jQuery: 1.1.2
Interface Elements: 1.2

I'm new to jQuery and I'm using the slide FX effect from Interface
Elements. I'm currently using the SlideOutLeft and SlideInLeft event.
And for some reason when I use a callback parameter, which should get
called after the effect has finished, according to the documentation
from the Interface Elements web site (http://interface.eyecon.ro/docs/
fx#). But for some reason the function is being called at the start of
the effect. Also there is a third parmeter for easing but this is not
working.

I've included the code below. Please can someone help with what I've
done wrong or is there a bug with the scripts?

What I've included in the header:
print "<script src=\"/template/jquery.js\" type=\"text/javascript\"></
script>\n";
print "<script src=\"/template/interface.js\" type=\"text/javascript
\"></script>\n";
print "<script src=\"/template/custom.js\" type=\"text/javascript\"></
script>\n";     //my own script for jQuery


//my jQuery code
$(document).ready(function() {
        $("#az").html("Hide: ");

        $("#az").toggle( function () {
                $('#site-az .nextPrevious').SlideOutLeft(1000, slideComplete());
        }, function () {
                $('#site-az .nextPrevious').SlideInLeft(1000);
                $("#az").html("Hide: ");
        });

        function slideComplete()
        {
                $("#az").html("Show:");
        }
});