What is Koro's failure in "Whale Rider" and why?

Koro fails to recognise his grand-daughter, Paikea, as the
next leader of the Whangara tribe.  Koro Apirana is a Maori chief of a small community
in coastal New Zealand (the Maori are the indigenous people of New
Zealand.)

Koto's  people once shared an identity strongly
rooted in their cultural heritage and proud of their traditions.  Now they are
dispirited soft-drug users, dependent on welfare, lacking a sense of past, purpose or
direction.

Koro Apirana traces his ancestry back to the
myth of Paikea, who rode a whale from Hawaiki to establish the Whangara community in New
Zealand.  The first-bon son inherits the
chieftanship.

Koro, is initially disappointed in his
first-born son, Porourangi, who is more interested in pursuing his artistic career
internationally, than in becoming the next chief.  This could be considered Koro's first
failure: that he fails to acknowledge his son's aspirations talent and  right to
determine his own future.

Similarly, he fails to
acknowledge the potential of his second son because he is so driven by his vision of a
patri-lineal leadership restoring the integrity of his
people.

However, his biggest failure is his blindness, in
the face of all evidence, that his grand-daughter, actually possesses all of the
leadership qualities for the future of the tribe that he is seeking - because a female
leader is unthinkable.  Paikea's twin brother  (and her mother) died when she was born,
and so Koro is fixated on the presumption that the dead twin was the legitimate
chief.

Eventually, Koro has to affirm, not merely the
exceptional abilities of his grand-daughter, but that, for his people to retrieve pride
and security in their cultural identity, they may need, in Paikea's words, "lots of
leaders", so that "everyone will be strong, not just the ones that have been
chosen."