Dialog error in IE 8

Dialog error in IE 8

I am trying to open a dialog box when someone drags a "step" box into a droppable. 

In the ready function I declared the dialog like this:
 $('#addStepPopUP').dialog({ autoOpen: false, modal: true })

Then on the droppable event I make a call to this div to open as so:
  $("#dropbox").droppable({
        drop: function (ev, ui) {
            if ($(ui.draggable).hasClass("newStep")) {
                $("#addStepPopUP").dialog('open');

This works for the first DIALOG (and subsequent ones in Firefox :(  ) .... but on my second dialog attempt in IE8 I get an error (invalid argument) -- and of course I cannot figure out how to use their terrible debugger.... but have captured what is happening in VStudio (see images below).  ** It appears that the ZIndex is coming back as NAN -- not sure why or if I am doing something wrong here. 

Any help would be very much appreciated.


F is the page
b is ZIndex and
d is NAN .....  so its trying to set Zindex to nan which I get why that causes the error....but dont know how to fix it from trying to do this in IE???

I AM THINKING that I need to rebind the dialog functionality back to the div although I cant yet figure out how to do it.