Safari 4.0.4中的window.location.hash不会增加history.length

I have a javascript error at the Safari 4.0.4 browser. I'm using AJAX navigation for the browser, in order to navigate between the result of my AJAX request, but the problem is that sometimes (i couldn't found the exact reasone) the history.lenght stays at the same count, instead of increase its value.I have a javascript error at the Safari 4.0.4 b