[jQuery] newbie problem with jQuery

[Mfoniso]

Hi all,

I'm new to jQuery so please pardon the hazy subject line.

Please see the code below:

function callback_function(xml){
// this function is called after an ajax post request, using jQuery
1.2.1
//the xml returned does have a <test> tag (which the alert shows)

    alert(xml); // this line works just fine
    var t = $("test", xml).text(); // this lines generates the error
below

//error message: ret[i].getElementsByTagName is not a function
}