project training - Tasks using multiple resources

I am using Project 2007 and trying to schedule tasks that use more than one resource, for example a meeting that both Joe and Jim need to attend. If I make the duration one day and allocate both resources, the Resource Usage shows Jim allocated for 7.5 hours and Joe allocated for 0 hours, so Joe is scheduled for other tasks that day.

If I make the meeting for a specific date, both Jim and Joe are both allocated for 7.5 hours. Any other Constraint Type gives the above results, regardless of the Task Type applied.

Any ideas?