Expressions that refer to DataWindow data are not verified until execution of your application.
When your script is compiled, PowerBuilder does not verify the parameters of the expression that follow the Object property. Your application can select or change the DataWindow object in a DataWindow control at runtime without invalidating the compiled script.
If the datatype of the expression is not compatible with how the expression is used, or if the specified rows or columns do not exist, an error will occur at runtime.
You can handle the error by surrounding the expression in a try-catch block and catching any DWRuntimeErrors, or by writing a script for the DataWindow control’s Error event.