[horde] language problem imp and/or turba

[alois blasbichler]

hello list
we use horde horde 2.2 and imp 3.2 and turba 1.1
we use Openldap (2.1.4) for user accounts, preferences and turba
and apache 1.3.26 with php 4.2.2

my problem are the german special charakters :umlaute :
with default settings i see the umlaute (ö ä ü)im IMP correct but in Turba 
(ldap) not.
If i change in horde/config/lang.php 
$nls['defaults']['charset'] = 'ISO-8859-1';
to
$nls['defaults']['charset'] = 'UTF-8';

and i cancel in turba/config/sources.php the line
 'encoding' => 'utf8',

then i see the umlaute im Turba (ldap) correct but in IMP not

for me is a problem with ldap-turba
but with another Ldap-Browser i see the umlaute in ldap correctly

maybe somebody can help me or have the same Problems

thank you 
luis