[imp] Horde Groupware Webmail Edition 5.1.1 - ERROR: User is not authorized for imp

[Emanuele Magno]

Hello everybody,
I state thatwe already use a previous Horde webmail release (4.0.7)  
that works. (it use mysql, openldap, postfix, dovecot ecc.)

Now, I installed and configured Horde Groupware Webmail Edition 5.1.1 
and IMP module without problem, setting ldap backend for the authentication
I can log in but I have the following response: ERROR User is not 
authorized for imp
I tried to find out where I'm wrong but without success.
The block error reports:

*A fatal error has occurred*

*User is not authorized for imp*

1. require() /var/www/html/horde/services/portal/edit.php:40
2. require() /var/www/html/horde/templates/portal/edit.inc:29
3. Horde_Core_Block_Collection->isEditable() /var/www/html/horde/templates/portal/layout.inc:80
4. Horde_Core_Block_Collection->getBlock() /usr/share/pear/Horde/Core/Block/Collection.php:464
5. Horde_Registry->pushApp() /usr/share/pear/Horde/Core/Block/Collection.php:117


      Details


        The full error message is logged in Horde's log file, and is
        shown below only to administrators. Non-administrative users
        will not see error details.

Horde_Exception_PushApp Object
(
     [application] => imp
     [details] =>
     [logged] => 1
     [_logLevel:protected] => 0
     [message:protected] => User is not authorized for imp
     [string:Exception:private] =>
     [code:protected] => 1
     [file:protected] => /usr/share/pear/Horde/Registry.php
     [line:protected] => 1513
     [trace:Exception:private] => Array
         (
             [0] => Array
                 (
                     [file] => /usr/share/pear/Horde/Core/Block/Collection.php
                     [line] => 117
                     [function] => pushApp
                     [class] => Horde_Registry
                     [type] => ->
                     [args] => Array
                         (
                             [0] => imp
                         )

                 )

             [1] => Array
                 (
                     [file] => /usr/share/pear/Horde/Core/Block/Collection.php
                     [line] => 464
                     [function] => getBlock
                     [class] => Horde_Core_Block_Collection
                     [type] => ->
                     [args] => Array
                         (
                             [0] => imp
                             [1] => imp_Block_Summary
                         )

                 )

             [2] => Array
                 (
                     [file] => /var/www/html/horde/templates/portal/layout.inc
                     [line] => 80
                     [function] => isEditable
                     [class] => Horde_Core_Block_Collection
                     [type] => ->
                     [args] => Array
                         (
                             [0] => imp
                             [1] => imp_Block_Summary
                         )

                 )

             [3] => Array
                 (
                     [file] => /var/www/html/horde/templates/portal/edit.inc
                     [line] => 29
                     [args] => Array
                         (
                             [0] => /var/www/html/horde/templates/portal/layout.inc
                         )

                     [function] => require
                 )

             [4] => Array
                 (
                     [file] => /var/www/html/horde/services/portal/edit.php
                     [line] => 40
                     [args] => Array
                         (
                             [0] => /var/www/html/horde/templates/portal/edit.inc
                         )

                     [function] => require
                 )

         )

     [previous:Exception:private] =>
)





Also, the following imp configuration file ( 
horde/imp/config/backends.local.php) seems not to be considered



/.....//
//// IMAP server//
//$servers['imap'] = array(//
//    // ENABLED by default; will connect to IMAP port on local server//
//    'disabled' => false,//
//    'name' => 'UNIBA IMAP Server',//
//    'hostspec' => 'mail.uniba.it',//
//    'hordeauth' => true,//
//    'protocol' => 'imap',//
//    'port' => 143,//
//    // Plaintext logins are disabled by default on IMAP servers (see 
RFC 3501//
//    // [6.2.3]), so TLS is the only guaranteed authentication 
available by//
//    // default.//
//    'secure' => 'tls',//
//);//
//...../


Please, someone help me understand where I'm wrong ?
Tanks in advance
Emanuele