how to pop up dropdown list in gridview using jquery

i have a input button inside the templatefield,where 1st input button only popup the dropdownlist inside gridview...remaining button are not firing....what is the problem? help me friends..
$(document).ready(function ()
{
$("#btnassign").click(function (e)
{
ShowDialog(false);
e.preventDefault();
});
inside itemtemplate, input button id is btnassign .