[jQuery] .html() causes null IE

[Jose Alfonso]

Hi,
I am pretty new to jQuery and I am using the tablesorter plugin and I
am getting a .html() is null or not an object error within a custom
parser

the code

var ts = $.tablesorter;

                        // add parser through the tablesorter addParser method
                        ts.addParser({
                                   id: "empnames",
                                   is: function(s) {
                                       return false;
                                   },
                                   format: function(s) {
                                           // make an object of the string
                                           var strobj = $($.trim(s));
                                           return 
strobj.find("span").html().toLowerCase();
                                   },
                                   type: "text"
                        });

In that case is an object but as soon as I add .html() it returns null
in IE. It works fine in Safari and Firefox.
I am using jQuery 1.3.2 and tablesorter 2.0
I am trying to make it sort the text that's in a span. If anyone has a
better technique to do it it's also appreciated.

thanks