Unable to delete - fatal error

I have a mostly blank editable grid application for testing delete with dependancies.

I have 4 dependancies setup, 2 of which have another 3 nested.

When I click delete on the record, I get a fatal error. Is this a known bug?

Fatal error: Uncaught Error: Call to a member function Close() on boolean in /Library/WebServer/Documents/scriptcase/app/protect/test_delete/test_delete_apl.php on line 4093

It seems that as soon as I have a 2nd level dependancy (table_self -> child -> child_2) the the above fatal error is thrown. I have 4 2nd level tables, I tried them each one by one and each gives the error.