Why can most African countries not host peaceful elections?

Kenya had reports of arson and violence in the aftermath of its 2008 elections and live media coverage was banned during the crisis.

Prior to the results from Ghana's run-off elections being revealed in 2009, NDC supporters reportedly converged on the election headquarters demanding that Akufo-Addo or Mills be declared the victor, but riot police and armed soldiers were called in to keep the peace.

Zimbabwe's 2008 presidential election was rife with accusations of fraud and ballot rigging after the first round of results were only released a month later. The period following the first round was marked by political violence.

Just last week Joao Bernardo Vieira, president of Guinea-Bissau, was shot dead by soldiers and yet the country's citizens went on the next day with business as usual, barely mourning their fallen leader.

Granted, every African country has its own economic and socio-political backgrounds that are the cause and effect behind these digressions.
Why can most African countries not host peaceful elections?