[imp] no thumbnails

[mig at mailbox.org]

Hi,

Your advice is appreciated.

System:Ubuntu 12.04
Horde (horde) 5.1.6
Mail (imp) 6.1.7

I have a little thumbnail problem. I installed Horde webmail just a few
days ago and I remember that thumbnails where displayed but now they 
are
not. I had “PECL Imagick Library” and I tried “Imagemagick” now and
its not working. Logging looks not too bad but the thumbnail is not
displayed.
I have only the square for the image with an “x” on it.

May 28 11:29:22 myhost HORDE: [imp] convert command executed by
Horde_Image_im::raw(): /usr/bin/convert -size 300x300 
"/tmp/imghN7kob"'[0]'
-thumbnail 150x150 +profile "*" png:"/tmp/imgMEitgk" 2>&1 [pid 15123 on
line 155 of "/usr/share/php/Horde/Image/Im.php"]

The 2nd issue is that I cant see HTML messages. I tried to follow the 
WIKI
and created 2 files:

Horde/config/mime_drivers.local.php:
$mime_drivers['imp']['html']['inline'] = true;
imp/config/mime_drivers.local.php:
$mime_drivers['html']['inline'] = true;
HTML was not displayed.

Any ideas?
Thanks,
Mike