I am just thankful that Travelocity still provides this fare listing. Expedia 'removed' their similar feature a long time ago, supposedly because they were getting too many complaints about it. I've had success by carefully reading the fare rules and then trying to find flights to comply with everything. The calendar program probably only searches the most simple routings for availability when there may be other multi-segment options available.

Also, Travelocity's delay between the time of payment and when they actually issue the ticket makes me shy away from using them. IMO it is unacceptable, especially with e-tickets, to tell a customer the next day that it will not be possible to issue the ticket.