Why doesn't a scripted data type transformation work if the data type was already changed using the Expanded Data Panel

[Tim McCune 3]

I'm writing a script that manages data types but I've noticed that the script can't change the type of a column if that column's type has already been changed using the data type dropdown in the Expanded Data Panel.

But if the column's type has been changed by using Insert - Transformations - Change data types from the GUI, then the script can still change the data type.

If I go to the Expanded Data Panel, then "Go to table view" and "Source view", it appears that changing the data type using the Expanded Data Panel results in a fundamentally different transformation than you get from using "Insert" - "Transformations" - "Change data types".

Is it possible to alter the column type from a script after it's been changed with the Expanded Data Panel

Here's an example script:

from Spotfire.Dxp.Data import *

from Spotfire.Dxp.Data.Transformations import *

dataTable=Document.Data.Tables["Table1"]

arrayColumnSig = []

columnSig = DataColumnSignature("Column1", DataType.Integer)

arrayColumnSig.append(columnSig)

t=ChangeDataTypeTransformation(arrayColumnSig, DataType.Real)

dataTable.AddTransformation(t)