[horde] IMP: backends.local.php not working

[Jan Niggemann]

Hello list,

my horde installation is on one host while my email is on another one.
My understanding is that I need to put the config for my IMAP server  
in horde/imp/config/backends.local.php, is this correct?

In case this is correct, I have an issue:
I can't log into my email when I put the data in backends.local.php,  
the error being "wrong username or password". when I put the very same  
configuration at the end of backends.php then everything works.

I checked that backends.local.php has the correct permissions.
Is there anything else I might have done wrong?

This also applies to registry.local.php, where I changed a menu_parent 
setting...

jan