We have used ZFD 7 sp1 for some years but have previously only associated apps with users/groups. We have not kept our Zen up to date and we are still running the standard v7.0 sp1. No IRs or HPs. The backend is on NW6.5 sp8, eDir

I have recently setup a new app that I want to deploy to all our workstations. The app is set to force deploy and is associated with the OU containing all our workstations.

About 80 pcs installed the app within a short time but about 30 show no sign of doing so. From naldiag the app looks OK but has 'Not Installed' under 'Last Associated Time' and 'Never' under 'Last Run Time'. If I associate the app with a test user it can be run from app explorer so I think that it is OK.

To try and make the app deploy on these last 30 PCs I have done these things -

Many reboots
Uninstall of the Zen DM agent the re-install from the v7.0 sp1 MSI
Uninstall of the Zen 7.0 sp1 DM agent then installing the latest agent from the v7.0 sp1 ir3a MSI.

No changes in behaviour. What can I do to debug this?