Jonathan failed to rescue the Chibok girls for 2 reasons;
1. He refused to pay ransom in Euro, Dollar and Pound Sterling to Boko Haram Terrorists, and their sponsors 2. The Chibok girls were all Christians, and so even if he was willing and or had agreed to pay the ransom, the terrorists and their collaborators in government may not have released them.
Jonathan may have also known about all this, and that was probably why he declared that some members of his cabinet were Boko Haram members!
The abduction of the Dapchi girls presents a different scenario altogether. All the girls are Moslems with the exception of Leah Sharibu who is a Christian, and she was not released by Boko Haram because of her Christian faith.
It has been widely reported that, Buhari paid humongous sums of money in foreign currency to the Boko Haram Terrorists as ransom for the release of the girls. Buhari has however, denied this allegation.
It is about religion and money.