Hello cs31415,

I apologize for the delay of my response.

I tested the code snippet you have provided, using ActiveCellChange event. I was able to get successful results.

Below is a snippet of the function: 

protected void UltraWebGrid1_ActiveCellChange(object sender, Infragistics.WebUI.UltraWebGrid.CellEventArgs e)
    {
        e.Cell.Value = "Infragistics";
        e.Cell.Value = e.Cell.Value + "¹";
    }

Please let me know if you have any questions.

Hello cs31415,

I am currently researching on this case.

I will provide you with more information before the week ends.

Thank you.