Ok, you can see your ZD(s) under the Inventory page ok though, right? Then, according to the User Guide...
Viewing ZoneDirector APs
Follow these steps to view a list of APs reporting to a ZoneDirector device.
1 On the List of ZDs table, display the ZD device that includes the APs you want
to view. When the ZD device does not appear on the table, search for it as
described in Searching for ZoneDirector Devices.
2 In the List of ZDs table, click the View More ZD Info link. FlexMaster displays
the ZD Detail section at the bottom of the window.
Can you click the 'View More ZD Info' link for your ZD, and does the lower pane fill with attached AP info?