Rules + Folders

I have created a folder under INBOX named “CPC” and this is the error message I get. What am i doing wrong? Jessie

[IMAP] Creating or updating folder ‘/Inbox/CPC’ failed due to the following error: Invalid mailbox name: Name must not have ‘/’ characters (0.001 + 0.000 secs).

As far as I know, not all IMAP servers allow subfolders in the inbox. Does it work in webmail or with another email client?