DB can only be reopened after DTP relaunch


I have a strange thing goin’ on here: When I close a database it disappears from DTPs radar: It will not open this DB again, only after it was quitted and relaunched.
Unquitted, the DB will not open from a doubleclick or select + cmd-O in the Finder, nor from DTP (menu “Open…”).
What is this? How can I prevent it?


Did you really close the database? Or just close all windows? Then a new window should appear after clicking on DTP’s Dock icon or after choosing File > New window.

Ah, that was my error, then. I thought if all windows were gone than the DB was closed, too.

Thanks for pointing me to the right direction!