Opens fine for me ......I see that you are on Designer 7 that might be
the issue. Here is the code that I used to add then move the subform://
Invoke the Instance Manager to add one instance of the detail
subform.details._detail.addInstance(1);//Get the total number of detail
subformscount = details._detail.count;//Ask the user where they want to
put the subformloc = app.response("Please enter the row number where you
want the new row to appear:");//Move the subform to the desired location
(note...