Enabling Ex2K IM users in AD

I’ve got Exchange 2000 IM running. Using the AD Users/Computers MMC from a remote system to enable a user for IM doesn’t work. After clicking “Enable”, the dialog boxes are greyed out. The only place I can enable IM users is from the Exchange server. I’ve tried from 2 other systems. Other than this, the systems and the MMC’s function just fine.

I’d like to be able to manage this from other MMC’s. Any idea why this is happening? I can manage all my other Exchange features from my PC. Enabling IM appears to be the only Exchange problem I’m having.