I've modified the portal to allow administrators to see the Displayed Owner and Owner when searching for Groups. What I'm wondering is how can I modify that so those two columns are sortable? Edit- All other colums listed like Display Name, email, description or domain are sortable.

I guess the reason is that Owner is a reference type while other attributes are strings.

I guess the reason is that Owner is a reference type while other attributes are strings.

Bump...Can I get an answer on this? I would very much like to make those columns sortable if possible.

Nothing on this? Is Eugene correct?

I believe he is. Looking at one of my implementations I render reference attributes and multivalue reference attributes and neither are sortable. This makes sense too, as the underlying data is a GUID, well a UniqueIdentifier. Note reference attributes in the search scope results result in loads of extra read traffic (to resolve each reference) and slow down the portal considerably in what I've seen. I ended up removing almost all of mine.