Hi makumbi,
$("[id*=Image1]").click(function () {
$('#dialog').html('');
$('#dialog').append($(this).clone());
$('#dialog img').css('height', '250');
$('#dialog img').css('width', '260');
$('#dialog').dialog('open');
});
Change above line of code with below.
Using the code Magnify selected ASP.Net GridView Image using jQuery i have modified the code.
$('body').on('click', "[id*=Image1],[id*=gvFiles] .imgData", function () {
$('#dialog').html('');
$('#dialog').append($(this).clone());
$('#dialog img').css('height', '250');
$('#dialog img').css('width', '260');
$('#dialog').dialog('open');
});