My problem is that when I select a country for the first time the states comboBox shows the number "1" which is the country "ID", and the states list of the states when I click the comboBox is ok.

My question it is why the value "1" is setted by defaut when I select the country?

I have the following code to retrieve the states when a country is selected:

protected void ComboBoxContrySelect(object sender, AjaxEventArgs e)
{
    string id = this.ComboBoxBILLINGCOUNTRYIDField.SelectedItem.Value.ToString();
    this.ObjectDataSourceComboBoxFechStateForCountry.SelectParameters["COUNTRYID"].DefaultValue = id;
    this.StoreComboBoxState.DataBind();
}
And the following are the fields:

<ext:FormLayout ID="FormLayout7" runat="server" LabelAlign="Top">
    <ext:Anchor Horizontal="80%">
        <ext:ComboBox 
            ID="BILLINGCOUNTRYIDField"
            StoreID="StoreComboBoxCountry" 
            runat="server" 
            Editable="false"
            ValueField="ID" 
            DisplayField="NAME" 
            FieldLabel="Country">
            <AjaxEvents>
                <select OnEvent="ComboBoxContrySelect"/>
            </AjaxEvents>
        </ext:ComboBox>
    </ext:Anchor>
    <ext:Anchor Horizontal="80%">
        <ext:ComboBox 
            ID="BILLINGREGION2IDField" 
            runat="server" 
            FieldLabel="State"
            StoreID="StoreComboBoxState" 
            EmptyText="Select a state..."
            ValueField="ID" 
            DisplayField="NAME" 
            ForceSelection="true" 
            />
    </ext:Anchor>
Thanks,