spacing between suggestion box and textbox for ajax autocomplete extender

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ASP.NET

Ajax-toolkit

I use ajax autocomplete extender in my page, everything work fine. the only problem is the suggestion box should be under the textbox, but it appeal a grap about 20~25px lower the textbox border. i hope my description about the problem is clear. Hope have solution for that.
thank you

<style type="text/css">
.AutoExtender {
    border: solid 1px #006699;
    line-height: 25px;
    background-color: White;
    list-style: none;
    margin-left: 0px;
    padding-left: 0px;
}
.FillInText {
    border: 1px solid #C0C0C0;
    background-color: #FFFFFF;
    font-size: 12pt;
    vertical-align: middle;
    font-family: 'Times New Roman' , Times, serif;
    height: 20px;
}
</style>

<asp:TextBox ID="txtName" runat="server" CssClass="FillInText" Width="197px"></asp:TextBox>
<ajaxToolkit:AutoCompleteExtender ServiceMethod="SearchCustomers" MinimumPrefixLength="1" CompletionListCssClass="AutoExtender"
CompletionInterval="10" EnableCaching="false" CompletionSetCount="15" TargetControlID="txtName"
ID="AutoCompleteExtender1" runat="server" FirstRowSelected="false">
</ajaxToolkit:AutoCompleteExtender>