[Mediawiki-l] Error in Redering Image

[Andreas Koch]

Hello,

we have the problem that some Images (all made the same way) 
are not able to create a thumbnail or something else.
If I have the following line in it:
----
[[Bild:Pkt 1month-link-usage all.gif|thumb|left]]<br>
---

but this works
---
[[Bild:Pkt conf-reports.png|thumb|left]]<br>
---
-------------------
Warning: call_user_func(imagegif) [function.call-user-func]: First argument
is expected to be a valid callback in
/srv/www/htdocs/gk_oracle/includes/Image.php on line 1159
Warning: Cannot modify header information - headers already sent by (output
started at /srv/www/htdocs/gk_oracle/includes/Image.php:1159) in
/srv/www/htdocs/gk_oracle/includes/OutputPage.php on line 421
Warning: Cannot modify header information - headers already sent by (output
started at /srv/www/htdocs/gk_oracle/includes/Image.php:1159) in
/srv/www/htdocs/gk_oracle/includes/OutputPage.php on line 449
Warning: Cannot modify header information - headers already sent by (output
started at /srv/www/htdocs/gk_oracle/includes/Image.php:1159) in
/srv/www/htdocs/gk_oracle/includes/OutputPage.php on line 450
Warning: Cannot modify header information - headers already sent by (output
started at /srv/www/htdocs/gk_oracle/includes/Image.php:1159) in
/srv/www/htdocs/gk_oracle/includes/OutputPage.php on line 509
-------------------

Thanks for Help

Andreas Koch
Service