Sub-folder disappeared!

I created a sub-folder under Inbox yesterday, but now the sub-folder has disappeared!
I am using eM to access my yahoo mail.
Whan I go to yahoo, I can see the sub-folder and its mails (thank god!) but in eM, the sub-folder is not visible.

Hi, Yahoo does not support subfolders in eM Client. There is problem with its implementation of IMAP protocol.