Hi Vladimir, yes I've referenced both the Telerik.Charting.DLL and the Telerik.Web.UI DLL in the project, in my ASPX page I have the declarations set as
<%
@ Register TagPrefix="telerik" Namespace="Telerik.Web.UI" Assembly="Telerik.Web.UI" %>
<%
@ Register TagPrefix="telerik" Namespace="Telerik.Charting" Assembly="Telerik.Charting" %>
The part of the code where it's complaining is the Telerik.Charting.ChartItemDataBound
protected void RadChart1_ItemDataBound(object sender, Telerik.Charting.ChartItemDataBoundEventArgs e)
{
if (e.SeriesItem.YValue > 30)
{
e.SeriesItem.ActiveRegion.Tooltip = "Attention! Temperature too high! " + '\n';
}
else if (e.SeriesItem.YValue < 10)
{
e.SeriesItem.ActiveRegion.Tooltip = "Attention! Temperature too low! " + '\n';
}
e.SeriesItem.ActiveRegion.Tooltip += ((DataRowView)e.DataItem)["Measurement"].ToString() + ": Temperature: " + e.SeriesItem.YValue;
}
I hope this helps, this is the example of your web site that tells me how to use the Tooltips?
Cheers,
Pete