So why doesn't this film "work"?

The Lighthorsemen seems to have all the elements to succeed including: a great and well known story, a massive budget, a huge cast, an established director, half a dozen scenic locations ranging from Corryong in the Victoria High Country to the semi-desert of the Flinders Ranges in northern South Australia, etc.

But when all those elements are put together, the film isn't terribly interesting or exciting, the characters are unsympathetic and it feels a bit forced and dull. This isn't just my opinion, the film was a failure at the box office and is almost never shown on television (although it was on YouTube when I posted this).

As a contrast, Breaker Morant (also on YouTube albeit with Serbo-Croat? subtitles) is another film about Australian mounted infantry and was made just 7 years earlier. It had a tiny budget, a small cast, a director who was almost unknown at the time, only two locations and no spare money for things like helicopters to film sweeping landscape shots. However that film was a huge hit and remains one of the most popular and well reviewed Australian films ever.

So why doesn't The Lighthorsemen work? Is it the script, the direction, the acting or something else?