i am trying to update plugsins and themes etc, but find

Hi, i am trying to update plugsins and themes etc, but find that the bulk update feature does not work?

Does not matter if doing via wpmu dev section or plugins sections or updates section all get is message

The update process is starting. This process may take a while on some hosts, so please be patient.

Enabling Maintenance mode…

Disabling Maintenance mode…

All updates have been completed.

but the updates do not occur?

I have another wpmu install on same server and that works fine?

any ideas?