Exchange - Sharing Calendars

[ICTSM]

Don't know if this is the right place, but here goes...


I have user A on our domain wishing to share his calendar to user B on another domain.

When I click 'share my calendar...' a windows pops up and asks for the recipients email address. I type in user B's address I get the following message...

'Calendar Sharing is not available with the following entries because of permission settings on your network.'

(see attachment)

I have never received any training on an Exhange system, so I'm rather stuck at the moment...and if anybody could point me in the right direction I would be eternally grateful.