PM NOTIFICATION TAB

We have configured a PM Notification with 4 tabs. Screen structure for extended view 10\TAB01 - Notification 1, 10\TAB03 - Additional data 2, 10\TAB09 - Additional data 3, 10\TAB10 – Item and 20\TAB01 – Item overview. Activity category is left blank. When the Notification is created or viewed in the change mode, all 4 tabs are displayed, however when viewed in the display mode, the item tab is not displayed. I have tried adding activity categories for 10\TAB10for each of the activities H, V and A. But that overrides the other tabs such that only the items tab is displayed. Any help you can provide would be appreciated. Perhaps there is a Note required?