Why could Charley not able to reach the third level again?

Dear Student 

The first time round, he found the third level by accident. When he reached the ticket-counter, he realised that the currency he had with him was not useful as it belonged to a different period. He went back to convert his three hundred dollars into the “old-style currency” that could enable him to buy two tickets to Galesburg. However, when he returned to the Grand Central, he could not find the corridor leading to the third level. He couldn’t go back looking for the third level as his wife was too worried about him. Moreover, he himself had stopped looking for it after sometime.

Regards