DevExpress ASPxComboBox not filtering <p>I have an ASPxComboBox from the DevExpress suite and am trying to get it filtered. If I click on the dropdown button of the combo box it will show the first few of the query as if the filter is empty.</p> <p>If I try to populate the filter, or scroll down to see more, it will just provide a perpetual "Loading" state. The stored procedure returns the correct results when ran with appropriate parameters. What could be the problem?</p> <p>EDIT: I have been following this tutorial on the DevExpress site: <a href="http://demos.devexpress.com/ASPxEditorsDemos/ASPxComboBox/LargeDataSource.aspx" rel="nofollow">http://demos.devexpress.com/ASPxEditorsDemos/ASPxComboBox/LargeDataSource.aspx</a></p> <p>EDIT (again): OK if I remove the line: </p> <pre><code>&lt;ClientSideEvents BeginCallback="function(s, e) { OnBeginCallback(); }" EndCallback="function(s, e) { OnEndCallback(); } " /&gt; </code></pre> <p>from the combo box it will hit a break point in <code>cboInstructor_OnItemsRequestedByFilterCondition_SQL</code>, but on going to the <code>DataBind()</code> it will thorw the error:</p> <blockquote> <p>Index (zero based) must be greater than or equal to zero and less than the size of the argument list.</p> </blockquote> <p>ASP file</p> <pre><code>&lt;form id="form1" runat="server"&gt; &lt;div&gt; &lt;dxe:ASPxComboBox ID="cboInstructor" runat="server" Width="100%" EnableCallbackMode="True" CallbackPageSize="10" IncrementalFilteringMode="Contains" ValueType="System.Int32" ValueField="employee_id" OnItemsRequestedByFilterCondition="cboInstructor_OnItemsRequestedByFilterCondition_SQL" OnItemRequestedByValue="cboInstructor_OnItemRequestedByValue_SQL" TextFormatString="{1} {2}" DropDownStyle="DropDown" DataSourceID="SqlDataSourceInstruct" &gt; &lt;Columns&gt; &lt;dxe:ListBoxColumn FieldName="display_forename" /&gt; &lt;dxe:ListBoxColumn FieldName="display_surname" /&gt; &lt;/Columns&gt; &lt;ClientSideEvents BeginCallback="function(s, e) { OnBeginCallback(); }" EndCallback="function(s, e) { OnEndCallback(); } " /&gt; &lt;/dxe:ASPxComboBox&gt; &lt;asp:SqlDataSource ID="SqlDataSourceInstruct" runat="server" ConnectionString="Server=160.10.1.25;User ID=root;Password=password;Persist Security Info=True;Database=central" ProviderName="MySql.Data.MySqlClient" SelectCommand="GetUser" SelectCommandType="StoredProcedure"&gt; &lt;SelectParameters&gt; &lt;asp:Parameter Name="filter" Type="String" /&gt; &lt;asp:Parameter Name="startIndex" Type="Int32" /&gt; &lt;asp:Parameter Name="endIndex" Type="Int32" /&gt; &lt;/SelectParameters&gt; &lt;/asp:SqlDataSource&gt; &lt;/div&gt; &lt;/form&gt; </code></pre> <p>CS file</p> <pre><code>public partial class TestComboBox : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { } protected void cboInstructor_OnItemsRequestedByFilterCondition_SQL(object source, ListEditItemsRequestedByFilterConditionEventArgs e) { ASPxComboBox comboBox = (ASPxComboBox)source; //SqlDataSourceInstruct.SelectCommand = // @"SELECT CONCAT(display_Forename, ' ', display_Surname) FROM (SELECT employee_id, display_forename , display_surname, @rownum:=@rownum+1 AS rn FROM central.user_record, (SELECT @rownum:=0) AS r WHERE CONCAT(display_forename, ' ', display_surname) LIKE @filter ORDER BY display_surname ASC) AS st where st.rn between @startIndex and @endIndex"; SqlDataSourceInstruct.SelectParameters.Clear(); SqlDataSourceInstruct.SelectParameters.Add("filter", TypeCode.String, string.Format("%{0}%", e.Filter)); SqlDataSourceInstruct.SelectParameters.Add("startIndex", TypeCode.Int64, (e.BeginIndex + 1).ToString()); SqlDataSourceInstruct.SelectParameters.Add("endIndex", TypeCode.Int64, (e.EndIndex + 1).ToString()); //comboBox.DataSource = SqlDataSourceInstruct; comboBox.DataBind(); } protected void cboInstructor_OnItemRequestedByValue_SQL(object source, ListEditItemRequestedByValueEventArgs e) { long value = 0; if (e.Value == null) return; if (!Int64.TryParse(e.Value.ToString(), out value)) return; ASPxComboBox comboBox = (ASPxComboBox)source; SqlDataSourceInstruct.SelectCommand = @"SELECT employee_id, display_surname, display_forename FROM central.user_record WHERE (employee_id = @ID) ORDER BY display_forename"; SqlDataSourceInstruct.SelectParameters.Clear(); SqlDataSourceInstruct.SelectParameters.Add("ID", TypeCode.Int64, e.Value.ToString()); comboBox.DataSource = SqlDataSourceInstruct; comboBox.DataBind(); } } </code></pre> <p>MySQL stored procedure</p> <pre><code>DELIMITER $$ USE `central`$$ DROP PROCEDURE IF EXISTS `GetUser`$$ CREATE DEFINER=`root`@`%` PROCEDURE `GetUser`(filter VARCHAR(50), startIndex INT, endIndex INT) BEGIN SELECT employee_id, display_Forename, display_Surname FROM (SELECT employee_id , display_forename , display_surname , @rownum:=@rownum+1 AS rn FROM central.user_record, (SELECT @rownum:=0) AS r WHERE CONCAT(display_forename, ' ', display_surname) LIKE filter ORDER BY display_surname ASC) AS st WHERE st.rn BETWEEN startIndex AND endIndex; END$$ DELIMITER ; </code></pre>