How does Charlie Oyster's education lead to conflict in the WPA office?

In Langston Hughes 1935's story "Gumption", the Oyster family (father and son) runs into trouble with the Works Progress Administration (WPA) after Charlie (son), who is educated, professionally trained after years of experience working for Mr. Bartelson as a typewriter and bookkeeper, is assigned a road worker job instead of an office job.

This decision angers the father, who after confronting the WPA agent, gets branded as a communist, and ended up being detained after trying to hit the agent after the police were called.

Therefore, the answer is: Charlie Oyster didn't got a job, one that he was trained and qualified to do, because he was discriminated for being black.