[jQuery] autocomplete caches against my will

[(null)]

Hi everybody,

I'm trying to use autocomplete (this one:
http://www.pengoworks.com/workshop/jquery/autocomplete.htm) to suggest
street names to the user while he types them.
Because there can be quite a lot streets I decided to limit the result
to 10 entries server-side.
Now the problem:
Let's assume I got 10 elements beginning with "An" and 10 elements
beginning with "At".
Now the user types an "A" into the textbox. Autocomplete contacts the
server which returns the 10 "An" elements. Now the user types in a
"t", resulting in an "At". Autocomplete seems to think it got all
elements starting with "A" and therefore all which start with "At",
searches it's list, finds none, shows none, although my server has 10
results for "At".

Now if I understand the docs right, the option matchSubset should
control/disable this behaviour:
matchSubset (default value: 1)
Whether or not the autocompleter can use a cache for more specific
queries. This means that all matches of "foot" are a subset of all
matches for "foo". Usually this is true, and using this options
decreases server load and increases performance. Remember to set
cacheLength to a bigger number, like 10.

But it doesn't.

Also the minChars - Option is completely ignored.

I'd really appreciate any help!

Here is my code:
As an explanation for the _cityDropDownList - part: The user first
selects the city and the street and of course I need to tell my site
in which city the street is supposed to be.

<script type="text/javascript">
        jQuery(function()
        {
                jQuery("#_streetTextBox").autocomplete("GetStreets.aspx", {
                        minChars:5,
                        matchSubset:0,
                        cacheLength:1
                });
                jQuery("#_cityDropDownList").change(function(event){
                        var ac = 
$("#_streetTextBox").autocomplete("GetStreets.aspx");
                        ac[0].autocompleter.setExtraParams({CityCode:
jQuery("#_cityDropDownList").val()});
                 });
        });
</script>