Header was duplicated

[Yiiiiii]

Firstly, really sorry for my poor english.
When numberCell: { show: true} is defined, table header is displayed correctly but when I inspect element DOM html, table header was duplicated.
In my case I want to use the input text in header but when I using jquery selector to select this input text, it cannot be selected.

Code: [Select]

var colModel;
colModel[1].title = "<div class='form-group'><label for='student'>Student</label><input type='text' class='form-control' id='student' style='width: 180px'/></div>";
....
$("#tabbe").pqGrid({
...
colModel: colModel
...
})

Jquery selector:

Code: [Select]

var student = $("#student");
Cannot get the element that is displayed in page.