How to get and set "SourceObject" value in program?

[aikea]

I create an empty form, drag a subform control to that and set that subform's "Source Object" property to "Table.Books".

I want to display the value stored in sourceobject property, so I placed a command button and typed in following code:

Private Sub Command1_Click()

MsgBox Me![Child1].Form.SourceObject

End Sub

After I clicked the button, I received an error:

Run-time error '2465'

Application-defined or Object-defined error

Is it possible to change the sourceobject property in program?