Getting items via webservice clears what was typed in.

[Edward]

Hello,
I have a Usercontrol with a RadComboBox that gets items via a webservice.
Everything is working correctly, however when I type, the search text disappears.
I had the same exact behavior with postbacks, but now its not posting back, and it is still doing the same thing.

Please take a look at the code below.
Here is the code for the RadComboBox:

<telerik:RadComboBox
    ID="cboContentProvider"
    runat="server"
    Width="225px"
    CheckBoxes="true"
    EmptyMessage="-- Select --"
    EnableLoadOnDemand="True"
    ShowMoreResultsBox="True"
    OnClientItemChecked="ItemChecked"
    EnableVirtualScrolling="True">
    <WebServiceSettings Method="GetContentProviderData" Path="../../WebService/BoomboxWs.asmx" />
    <ExpandAnimation Type="InOutElastic" />
</telerik:RadComboBox>

Here is the code for CP_ItemChecked:

function CP_ItemChecked(sender, eventArgs) {
    var data = '{ "type": "' + sender.get_id() + '", "id": "' + eventArgs.get_item().get_value() + '" }';
    $.ajax({
        type: "POST",
        url: "../../WebService/BoomboxWs.asmx/MarkSelectedItem",
        data: data,
        contentType: "application/json; charset=utf-8",
        dataType: "json",
        success: function (msg) {
        }
    });
}

Here is the WebMethod:

[WebMethod(EnableSession = true)]
public RadComboBoxData GetContentProviderData(RadComboBoxContext context)
{
    return GetRadComboBoxData(context, DtCp, DtCp.Count());
}

public RadComboBoxData GetRadComboBoxData(RadComboBoxContext context, List<GenericDataList> data, int itemsPerRequest = 20)
{
    var comboData = new RadComboBoxData();

    var itemOffset = context.NumberOfItems;
    var endOffset = itemOffset + itemsPerRequest;

    if (endOffset > data.Count())
    {
        endOffset = data.Count();
    }

    if (!string.IsNullOrEmpty(context.Text))
    {
        data = data.Where(q => q.Name.ToUpper().Contains(context.Text.ToUpper())).ToList();
    }

    comboData.EndOfItems = endOffset == data.Count();

    var result = new List<RadComboBoxItemData>(endOffset - itemOffset);

    result.AddRange(data.Take(endOffset).Skip(itemOffset)
        .Select(radItem => new RadComboBoxItemData {Text = radItem.Name, Value = radItem.Id.ToString(CultureInfo.InvariantCulture)}));

    comboData.Message = data.Any() ? String.Format("Items <b>1</b>-<b>{0}</b> out of <b>{1}</b>", endOffset, data.Count()) : "No matches";
    comboData.Items = result.ToArray();

    return comboData;
}