[imp] Invalid mailbox name

[dromero at fiec.espol.edu.ec]

Hi!

I have a problem with imp, i really don't know why appear this error, i
have made all and nothing work. I have installed postfix and cyrus, the
authentication is LDAP, all horde is fine, except when a user want save
their mail or create a folder.

For example:

Error  The folder "drafts" was not created. This is what the server said:
Invalid mailbox name

Error  There was an error saving this message as a draft.

What can i do with this

Can you help me???