[imp] User is not authorized for imp

[info at netfast.biz]

Hello, 

I have been trying hard for days to get horde groupware
5.1.1 webmail edition to work well and cannot get these 2
functionalities to work together: 

I get a "User is not authorized for
imp" Error message and no mail shows, in my curent setup - which uses
SQL authenication 

1) I want to allow new users to register, (this only
works if I use a SQL authentication backend - it does not work - i.e. no
register links are displayed if I use horde authentication and choose
imp.) 

2) I want users to be able to delete messages so they go into
the Trash directly, -( If I use horde / imp authentication, I see the
email messages, but cannot move them to Trash, although I can move them
to other folders I have created! I get IMAP Server error message - I am
using dovecot (with postfix on debian wheezy) - is there something I
need to do to tell horde to use dovecot specifically? (should I use
"localhost" or put the servers fqdn or IP address in - I have tried them
all and none work). It seems to make no difference if I disable
permissions, or leave permissions to deault, or add them all for
everyone. What is recommended here?  

There seems to be no decent
documentation about how to configure this thing at all. 

Thanks for
help. 

If I should be sending this to another mail list, please tell me
which one. I am new here. 

Ed