Autocomplete in JQuery is not working properly

Autocomplete in JQuery is not working properly

I am trying to use jquery auto complete .it is not working properly it
showing only one option every time i don't why i am getting this.
Code
var options_df1 = {
serviceUrl: '/'+company+'/city_names.html',
width: 230,
minChars: 1,
maxHeight: 500,
delimiter: /(,|;)\s*/,
onSelect: onAutocompleteSelect_df1,
deferRequestBy: 0, //miliseconds
params:{country: 'Yes'},
};
var onAutocompleteSelect_df1 = function(value_df, data_df) {
startlocation_df = data_df;
}