Shundo David Haye – Zen Priest

When Shenhui of Ho Chen came to study with Qingyuan, the master asked where he was coming from, and Shenhui said from Cao Xi. 
“What’s new in Cao Xi?” asked Qingyuan. 
When Shenhui remained silent, Qingyuan said, “Tiles and pebbles are still in your way”. 
Shenhui asked, “Do you have true gold to give to others?” 
Qingyuan said, “Even if I had some, how would you hold on to it?”

What is Shenhui’s error? If he couldn’t say anything about what he had learned before (at the Sixth Patriarch’s temple no less), how would he be able to do so in the future?