[horde] Nag ignores Rewrite or Get-based URLs

[Henning]

> > Horde active. Is there any way that Nag uses the rules without having to
> > turn the option in horde back on (Or alternatively having the DAV Server
> > work with the rewrite rules)?
> 
> Nag's routes are not affected by the "use pretty urls" configuration.  
> They are always used.
> 

Yep even turning on pretty URLs doesn´t help. Mod_rewrite is definitely
loaded and active. I tried logging and it came up with

[Tue Aug 13 22:00:27.537337 2013] [rewrite:trace2] [pid 5684]
mod_rewrite.c(468): [client x.x.x.x:62886] x.x.x.x - -
[www.domain.de/sid#7f8843e7b370][rid#7f8843dc60a0/initial] init rewrite
engine with requested uri /webmail/nag/t/save, referer:
https://www.domain.de/webmail/nag/task.php?actionID=add_task&tasklist_id=user
[Tue Aug 13 22:00:27.537431 2013] [rewrite:trace1] [pid 5684]
mod_rewrite.c(468): [client x.x.x.x:62886] x.x.x.x - -
[www.domain.de/sid#7f8843e7b370][rid#7f8843dc60a0/initial] pass through
/webmail/nag/t/save, referer:
https://www.domain.de/webmail/nag/task.php?actionID=add_task&tasklist_id=user

which looks ok to me, but still 404?! Did I miss something?

Regards

Henning