Group by is only available when done at design time.
<telerik:RadGrid ID="gridLockbox" runat="server" PageSize="20" PagerStyle-PageButtonCount="5" AllowMultiRowSelection="true"
OnNeedDataSource="gridLockbox_NeedDataSource" OnDetailTableDataBind="gridLockbox_DetailTableDataBind"
OnItemDataBound="gridLockbox_ItemDataBound" OnUpdateCommand="gridLockbox_UpdateCommand"
AllowPaging="true" AllowSorting="true" ShowGroupPanel="true" CellSpacing="0" Width="100%" Height="700px"
RenderMode="Lightweight" ShowFooter="true" Skin="WebBlue">
<GroupingSettings ShowUnGroupButton="True" CaseSensitive="false"/>
<ClientSettings>
<Scrolling AllowScroll="true" UseStaticHeaders="true" SaveScrollPosition="true" />
</ClientSettings>
<MasterTableView EditMode="PopUp" AutoGenerateColumns="false" AllowFilteringByColumn="true" DataKeyNames="TransUID"
AllowMultiColumnSorting="true" CommandItemDisplay="None" TableLayout="Fixed" Font-Size="10">
<DetailTables>
<telerik:GridTableView DataKeyNames="RecordId" Name="Details" Width="100%" AutoGenerateColumns="false" TableLayout="Fixed">
<Columns>
<telerik:GridBoundColumn DataField="FileOperation" HeaderText="File Operation" HeaderButtonType="None">
<HeaderStyle Width="180px" />
</telerik:GridBoundColumn>
<telerik:GridBoundColumn DataField="FileStatus" HeaderText="File Status" HeaderButtonType="TextButton">
<HeaderStyle Width="200px" />
</telerik:GridBoundColumn>
<telerik:GridDateTimeColumn DataField="CreatedDateTime" HeaderText="Created At">
<HeaderStyle Width="250px" />
</telerik:GridDateTimeColumn>
<telerik:GridBoundColumn DataField="Notes" HeaderText="Notes" HeaderButtonType="TextButton"></telerik:GridBoundColumn>
</Columns>
</telerik:GridTableView>
</DetailTables>
<GroupByExpressions>
<telerik:GridGroupByExpression>
<SelectFields>
<telerik:GridGroupByField FieldAlias="Date_Time" FieldName="Date_Time" FormatString="{0:MM/dd/yyyy}" HeaderValueSeparator=" from date: " />
</SelectFields>
<GroupByFields>
<telerik:GridGroupByField FieldName="Date_Time" SortOrder="Descending" />
</GroupByFields>
</telerik:GridGroupByExpression>
</GroupByExpressions>
<Columns>
<telerik:GridEditCommandColumn UniqueName="EditColumn" HeaderText="Edit" Exportable="false">
<HeaderStyle Width="50px" />
</telerik:GridEditCommandColumn>
<telerik:GridBoundColumn UniqueName="Lockbox" DataField="Lockbox" HeaderText="Lockbox" HeaderStyle-Width="180px" FilterControlWidth="70%">
<FilterTemplate>
<telerik:RadComboBox RenderMode="Lightweight" ID="cmbLockbox" DataSource='<%#LockboxNames %>' DataTextField="Name"
DataValueField="ID" Width="150px" AppendDataBoundItems="true"
SelectedValue='<%# ((GridItem)Container).OwnerTableView.GetColumn("Lockbox").CurrentFilterValue %>'
runat="server" OnClientSelectedIndexChanged="LockboxIndexChanged">
<Items>
<telerik:RadComboBoxItem Text="All" />
</Items>
</telerik:RadComboBox>
<telerik:RadScriptBlock ID="RadScriptBlock1" runat="server">
<script type="text/javascript">
function LockboxIndexChanged(sender, args) {
var tableView = $find("<%# ((GridItem)Container).OwnerTableView.ClientID %>");
tableView.filter("Lockbox", args.get_item().get_value(), "EqualTo");
}
</script>
</telerik:RadScriptBlock>
</FilterTemplate>
</telerik:GridBoundColumn>
<telerik:GridDateTimeColumn UniqueName="Date_Time" DataField="Date_Time" HeaderText="Date" DataFormatString="{0:MM/dd/yyyy}">
<HeaderStyle Width="180px" />
</telerik:GridDateTimeColumn>
<telerik:GridBoundColumn UniqueName="TransSource" DataField="TransSource" HeaderText="Trans Type" Display="false"></telerik:GridBoundColumn>
<telerik:GridNumericColumn UniqueName="Amount" DataField="Amount" HeaderText="Amount" DataType="System.Decimal" DataFormatString="{0:C}" FilterControlWidth="80%" Aggregate="Sum">
<HeaderStyle Width="140px" />
</telerik:GridNumericColumn>
<telerik:GridBoundColumn UniqueName="ABA_RT" DataField="ABA_RT" HeaderText="Routing number">
<HeaderStyle Width="200px" />
</telerik:GridBoundColumn>
<telerik:GridBoundColumn UniqueName="AccountNum" DataField="AccountNum" HeaderText="Account number">
<HeaderStyle Width="210px" />
</telerik:GridBoundColumn>
<telerik:GridBoundColumn UniqueName="CheckNum" DataField="CheckNum" HeaderText="Check Number">
<HeaderStyle Width="200px" />
</telerik:GridBoundColumn>
<telerik:GridBoundColumn UniqueName="FileOperation" DataField="FileOperation" HeaderText="File Operation">
<HeaderStyle Width="200px" />
<FilterTemplate>
<telerik:RadComboBox RenderMode="Lightweight" ID="cmbFileOperation" DataSource='<%#FileOperationNames %>' DataTextField="Name"
DataValueField="ID" Width="150px" AppendDataBoundItems="true"
SelectedValue='<%# ((GridItem)Container).OwnerTableView.GetColumn("FileOperation").CurrentFilterValue %>'
runat="server" OnClientSelectedIndexChanged="FileOperationIndexChanged">
<Items>
<telerik:RadComboBoxItem Text="All" />
</Items>
</telerik:RadComboBox>
<telerik:RadScriptBlock ID="RadScriptBlock2" runat="server">
<script type="text/javascript">
function FileOperationIndexChanged(sender, args) {
var tableView = $find("<%# ((GridItem)Container).OwnerTableView.ClientID %>");
tableView.filter("FileOperation", args.get_item().get_value(), "EqualTo");
}
</script>
</telerik:RadScriptBlock>
</FilterTemplate>
</telerik:GridBoundColumn>
<telerik:GridBoundColumn UniqueName="FileStatus" DataField="FileStatus" HeaderText="FileStatus">
<HeaderStyle Width="200px" />
<FilterTemplate>
<telerik:RadComboBox RenderMode="Lightweight" ID="cmbFileStatus" DataSource='<%#FileStatusNames %>' DataTextField="Name"
DataValueField="ID" Width="150px" AppendDataBoundItems="true"
SelectedValue='<%# ((GridItem)Container).OwnerTableView.GetColumn("FileStatus").CurrentFilterValue %>'
runat="server" OnClientSelectedIndexChanged="FileStatusIndexChanged">
<Items>
<telerik:RadComboBoxItem Text="All" />
</Items>
</telerik:RadComboBox>
<telerik:RadScriptBlock ID="RadScriptBlock3" runat="server">
<script type="text/javascript">
function FileStatusIndexChanged(sender, args) {
var tableView = $find("<%# ((GridItem)Container).OwnerTableView.ClientID %>");
tableView.filter("FileStatus", args.get_item().get_value(), "EqualTo");
}
</script>
</telerik:RadScriptBlock>
</FilterTemplate>
</telerik:GridBoundColumn>
<telerik:GridBoundColumn UniqueName="ImageFilePath" DataField="ImageFilePath" Display="false"></telerik:GridBoundColumn>
<telerik:GridNumericColumn UniqueName="PaymentId" DataField="PaymentId" HeaderText="Payment Id" FilterControlWidth="70%">
<HeaderStyle Width="120px" />
</telerik:GridNumericColumn>
</Columns>
<EditFormSettings EditFormType="WebUserControl" UserControlName="LockboxCtrl.ascx">
<PopUpSettings Modal="true" Width="1500px"/>
</EditFormSettings>
</MasterTableView>
</telerik:RadGrid>