Workaround for the NextPrevAndNumeric mode is to set the AssociatedControlID of the label

	protected void RadGrid1_ItemDataBound(object sender, GridItemEventArgs e)
	{
		if (e.Item is GridPagerItem)
		{
			GridPagerItem pager = e.Item as GridPagerItem;
			Label lbl = pager.FindControl("ChangePageSizeLabel") as Label;
			Panel pnl = lbl.Parent as Panel;
			RadComboBox combo = pnl.FindControl("PageSizeComboBox") as RadComboBox;
			lbl.AssociatedControlID = combo.ID;
		}
	}

	<telerik:RadGrid RenderMode="Lightweight" ID="RadGrid1" runat="server" DataSourceID="SqlDataSource1" AllowSorting="True"
						AllowPaging="True" GridLines="None" Width="100%" OnItemDataBound="RadGrid1_ItemDataBound">
		<PagerStyle Mode="NextPrevAndNumeric" Position="TopAndBottom" PageSizeControlType="RadComboBox"></PagerStyle>
	</telerik:RadGrid>
			
	<asp:SqlDataSource ID="SqlDataSource1" ConnectionString="<%$ ConnectionStrings:NorthwindConnectionString %>"
						ProviderName="System.Data.SqlClient" SelectCommand="SELECT CustomerID, CompanyName, ContactName, ContactTitle, Address, PostalCode FROM Customers"
						runat="server"></asp:SqlDataSource>