Unfortunately, in their latest update, PrintCentral were forced to remove the in-app printing capability for 'compliance reasons'. It appears as though they were able to offer in-app printing by means of an undocumented API (application programmer interface) in iOS, the iPad's operating system. Apple made them remove this feature, so now you have to print iWorks documents from PrintCentral itself - you cannot do this from within Pages. So, when you want to print a Pages document, you have to open it in PrintCentral and print it from there.
Some members - me included - have opted not to update our PrintCentral so that we can retain the in-app printing capability
Tim
Scotland