I am trying to use the 4 access methods (Apollo, Galileo, Sabre, WSpan) to get booking code availability on LX between BOS and DEL.

No problems (from beginning of March through to end of April) getting such information from BOS to DEL (via ZUR). However, trying the reverse direction, I either get a message that no flights available (esp with Galileo) or there is a error message stating something like this is not a valid itinerary. Why the problems with obtaining the information from DEL to BOS via ZUR; while full information seems to be forthcoming from BOS to DEL via ZUR? I also seem to have the same problems with access of such information for the individual flights: DEL-ZUR or ZUR-BOS (again on LX only)?