I've a combobox with paged store that use ItemTpl to render items.
When I select an item on the first page of dropdownlist, I see the correct text on the combobox but when I click on the trigger button to show me the dropdownlist and change page to any other then the first WITHOUT selecting an item, the text in combobox changes from the DisplayField value to ValueField value.
For example:
I click the trigger, select the first element of the first page with valueField ABC and displayField 'Example'. In the combobox appear 'Example'.
I reclick the trigger and change to page 2 in the drop down list. In the combobox appear 'ABC' though I never select an item...
The store look like this:

<ext:Store ID="MDAnagraficaDocStore" runat="server" AutoLoad="false" RemoteSort="true"
PageSize="5">
<Proxy>
<ext:AjaxProxy Json="true" Url="../XXXXX.asmx/YYYYY">
<ActionMethods Read="POST" />
<Reader>
<ext:JsonReader Root="d.Data" IDProperty="CodConto" TotalProperty="d.TotalRecords">
</ext:JsonReader>
</Reader>
</ext:AjaxProxy>
</Proxy>
<Model>
<ext:Model ID="mfAnagraficheDocumento" runat="server">
<Fields>
<ext:ModelField Name="CodConto" />
<ext:ModelField Name="RagioneSociale" />
<ext:ModelField Name="Cap" />
<ext:ModelField Name="Indirizzo" />
<ext:ModelField Name="Localita" />
<ext:ModelField Name="Provincia" />
<ext:ModelField Name="Paese" />
<ext:ModelField Name="PIVA" />
<ext:ModelField Name="CodFiscale" />
<ext:ModelField Name="Tipo" />
</Fields>
</ext:Model>
</Model>
<Sorters>
<ext:DataSorter Property="RagioneSociale" Direction="ASC" />
</Sorters>
</ext:Store>

and the combobox is this:

<ext:ComboBox ID="MDCmbAnagrafica" runat="server" Name="CodiceAnagrafica" DisplayField="RagioneSociale"
ValueField="CodConto" TypeAhead="false" Width="388" TriggerAction="All" ForceSelection="false"
PageSize="5" AllowBlank="false" MinChars="1" StoreID="MDAnagraficaDocStore" AnchorHorizontal="100%" QueryMode="Remote"
FieldLabel="Anagrafica" >
<ListConfig LoadingText="Ricerca..." ItemSelector="div.search-item" EmptyText="Scegliere un tipo documento..."
PageSize="5" Width="500">
<ItemTpl ID="MDAnagTemplate" runat="server">
<Html>
<div class="search-item">
<h3>
<div class="container">
<div class="lbl">Codice:</div>
<div class="data">{CodConto}</div>
</div>
{RagioneSociale}
</h3>
</div>
</Html>
</ItemTpl >
</ListConfig>
<Listeners>
<BeforeQuery Handler="delete this.lastQuery" />
</Listeners>
</ext:ComboBox>

How can I resolve this "reset" problem?