It's easy when using VBA code, like,
..ChartTitle.Characters.Text = "Hello"

But, setting a Text or Characters property of chartTitle always got an
exception. Is it possible doing that?

code excerpt in vb.net

objChart = objSheet.ChartObjects.Add(50, 40, 300, 200).Chart
objChart.SetSourceData(Source:=objSheet.Range("A1" ).Resize(cNumRows,
cNumCols))
objChart.ChartTitle.Characters.Text = "Hello" <---- here!!!

Thx in advance.