>I agree with you that this is what happens. But what puzzles me is why the container "check" for the alias used in the RowSource of the combo control (and of course does not find the alias) instead of first calling the INIT of the control. I have another form that has a container (also dynamically added) that uses exactly the same control and no problems there. Thank you for helping me understand the issue and hopefully get to the solution.

Properties are evaluated before .init() is run. So it tries to bind the rowsource to an alias which doesn't exist yet, hits an error and starts unloading your form.

You can't put cart ahead of the horse, so you need to set the .rowsource programmatically, in .init(), after (and if) the cursor is created.