Problem creating text box on Excel chart

I have a LS agent which creates an Excel chart from data in a Notes document. The agent is working well with one exception. After creating the chart I am trying to add a text box to the chart.

I used the Excel Macro recording facility which produced the following code for creating a text box…

ActiveChart.Shapes.AddTextbox(msoTextOrientationHorizontal, 10, 10, 40, 65).Select

Selection.Characters.Text = "Deeper"

I converted the code to LotusScript and here is the relevant portions of the code

Dim tchart As Variant

Set tchart = Excel.Charts("Chart1").

.

Dim textbox1 As Variant

Set textbox1 = tchart.Shapes.AddTextbox(1, 10, 10, 40, 65)

textbox1.Characters.Text  = "Deeper" 'This line results in "Automation object error"

I tried to use “Add Shape” in place of “AddTextbox”

Set textbox1 = tchart.Shapes.AddShape(1, 10, 10, 40, 65).TextFrame

textbox1.Characters.Text = "Deeper" 'This line results in "Automation object member not found"

In both cases the textbox or shape was added to the chart in the specified location but the statement to populate the text box or shape with text caused the indicated error.

I have extensively searched all the Notes/Domino forums, looked at all Excel code examples in the Sandbox, and searched the internet for a solution without success. Any suggestions would be greatly appreciated.