Certain Javascript (__doPostBack, Button.click()) is not firing

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C#

Javascript

Gridview

I have added the code below to Postback onkeypress. On the same Debug run, sometimes I am able to run perfectly but most other times it will skip one or two functions.

protected void gv_RowDataBound(object sender, GridViewRowEventArgs e)
{
    if (e.Row.RowType == DataControlRowType.DataRow)
    {
        if ((e.Row.RowState == DataControlRowState.Edit) ||
           (e.Row.RowState == (DataControlRowState.Edit | DataControlRowState.Alternate)))
        {
             e.Row.Attributes.Add("onkeydown", "javascript:if(event.keyCode == 13) {__doPostBack('" + gv.UniqueID + "', 'Update$" +
                        e.Row.RowIndex.ToString() + "'); $('#" + Button3.UniqueID + "').click(); __doPostBack('" + gv.UniqueID + "',  'Edit$" +
                        (e.Row.RowIndex + 2).ToString() + "'); return false; }");
        }
    }
}

I am using .Net Framework 3.5 and IE11 as browser.