facing problem in autocomplete search

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C#

ASP.NET

jQuery

i have a gridview control...on each add button click i create new row and on each delete button click i delete the last row...in each row there is a text box...in this textbox i wanna autocomplete search...but i get a error...

this is my code:

function automember(eval) {
    alert(eval.value);
    alert(eval.id);

    debugger;
    $(eval.id).autocomplete({
        source: function (request, response) {
            $.ajax({
                type: "POST",
                contentType: "application/json; charset=utf-8",
                url: "/InputSheet.aspx/GetAutoCompleteTour",
                data: "{'selCo':'" + document.getElementById(eval.id).value + "'}",
                dataType: "json",
                success: function (data) {
                    response(data.d);
                },
                error: function (result) {
                    alert("Error");

                }
            });
        }
    });
}

please help me out...