Like in billiards, with many balls (i.e. the ionosphere) on the table, paths are often not reciprocal enough to accomplish contact. That is why off the back of the beam contacts are made.
As well as the overall antenna pattern, multi-path and lobes factor in, too. The other stations may be running much more power and/or gain than you, making the effort lopsided.
All good suggestions to follow!
Mike WBØDZX