How to get the text contents (box value) of AutoCompleteBox?

Hi, I need to retrieve the text contents of AutoCompleteBox in Javascript (client side).

I tried this but it just alerts me nothing (blank result):

<script>

function CheckOE() {
            alert(document.getElementById('RadAutoCompleteBox1').value);
        }

</script>

<telerik:RadAutoCompleteBox RenderMode="Lightweight" runat="server" ID="RadAutoCompleteBox1" ClientID="RadAutoCompleteBox1" 
            autopostback="true"
            DataSourceID="blah" DataTextField="blah" DataValueField="blah" InputType="blah" Width="100%"
            AllowCustomEntry = "false"
            DropDownWidth="150px"
            onfocusout="CheckOE()"
            >

Any idea?

Thanks!