If else condition is not working?

I have three populated drop down list depends on text field. when i type some data in text field drop down list act on this text field. And if i do not type anything then three populated drop down list depend on each other accordingly.

My problem is::: If Else condition is not working properly.Only Else condition is working here.... But separately they are working fine.

My coding are in below:

    $(document).ready(function(){

  if ($('#station_name').val().length != 0)
    {
                            $('#station_name').on('change',function(){
                        var textID = $(this).val();

                        if(textID){
                                $.ajax({
                                type:'POST',
                                url:'ajaxData.php',
                                data:'station_name='+textID+'&action=entry',
                                success:function(html){
                                 $('#pref').html(html);

                                    $('#line').html('<option value="">-- 鉄道線を選択 --</option>');
                                    $('#station').html('<option value="">-- 駅を選択 --</option>'); 
                                    }
                            }); 
                        }else{
                            $('#pref').html('<option value="">-- 最初に都道府県を選択 --</option>');
                            $('#line').html('<option value="">-- 鉄道線を選択 --</option>');
                            $('#station').html('<option value="">-- 駅を選択 --</option>'); 
                        }
                    }); 

                    $('#pref').on('change',function(){
                        var prefID = $(this).val();
                        var textID = $('#station_name').val();
                        if(prefID){
                            $.ajax({
                                type:'POST',
                                url:'ajaxData.php',
                                data:'pref_cd='+prefID+'&action=e_line&station_name='+textID,
                                success:function(html){
                                    $('#line').html(html);

                                    $('#station').html('<option value="">-- 駅を選択 --</option>'); 

                                    }
                            }); 
                        }else{
                            $('#line').html('<option value="">-- 鉄道線を選択 --</option>');
                            $('#station').html('<option value="">-- 駅を選択 --</option>'); 
                        }
                    });

                    $('#line').on('change',function(){
                        var lineID = $(this).val();
                        var prefID = $('#pref').val();
                        var textID = $('#station_name').val();
                        if(lineID){
                            $.ajax({
                                type:'POST',
                                url:'ajaxData.php',
                                data:'line_cd='+lineID+'&action=e_station&pref_cd='+prefID+'&station_name='+textID,
                                success:function(html){
                                    $('#station').html(html);

                                }
                            }); 
                        }else{
                            $('#station').html('<option value="">-- 駅を選択 --</option>'); 
                        }
                    });

    }

    else 

    {  
                              $('#pref').on('change',function(){
                                var prefID = $(this).val();
                                if(prefID){
                                    $.ajax({
                                        type:'POST',
                                        url:'ajaxData.php',
                                        data:'pref_cd='+prefID+'&action=line',
                                        success:function(html){
                                            $('#line').html(html);
                                            $('#station').html('<option value="">-- 駅を選択 --</option>'); 

                                            }
                                    }); 
                                }else{

                                    $('#line').html('<option value="">-- 鉄道線を選択 --</option>');
                                    $('#station').html('<option value="">-- 駅を選択 --</option>'); 
                                }
                            });

                            $('#line').on('change',function(){
                                var lineID = $(this).val();
                                var prefID = $('#pref').val();
                                if(lineID){
                                    $.ajax({
                                        type:'POST',
                                        url:'ajaxData.php',
                                        data:'line_cd='+lineID+'&action=station&pref_cd='+prefID,
                                        success:function(html){
                                            $('#station').html(html);

                                        }
                                    }); 
                                }else{
                                    $('#station').html('<option value="">-- 駅を選択 --</option>'); 
                                }
                            });

    }
    $('#btn_eki').click(function(){
            var $option = $('#station option:selected');
            var station = $option.val();
            window.parent.add_tag(station, "", $('#wishtxt').html(),1);
            window.parent.$('#nearStForm' + $('input[name="wish"]').val()).slideUp();
            return false;
        });
    $('#wishtxt').html($('#form_eki [name="wish"]').val());
});