how to test a "Member of M:N schema type" virtual attribute in mapping condition

Dears,

Could you help me how to test a "Member of M:N schema type" virtual attribute in mapping condition"?

After read the doc "Synchronization Technology A walkthrough and reference" and follow the steps in the doc.

On Provisioning, groupOfNames member, It shows the error,

Unable to cast object of type ''VI.Projector.Database.DatabaseSystemObjectData'' to type ''System.IComparable''

The 1IM version is 8.1.2, 

Please help, very thanks ~~

David