OK well you're probably missing the Tab definitions from the underlying DNN tabs table. When the module is installed, it creates a 'Page Urls' page in the admin menu for each installed portal. The type of portal (parent/child) doesn't matter.
When you add portals after the module is installed, it runs a trigger which should create the page for the new portal.
So the problem can be narrowed down to either (a) the install not working or (b) the trigger for new portals not working. Were the portals without the page created after the module was installed, or were they there before?
Also, do you have access to run Sql Scripts against the database? For example, through Sql Server Management Studio? I can probably help you recreate the missing pages by providing some Sql.
-Bruce