[Koha] The following fatal error has occurred:can't call method

[Marius ADAHA]

I'm from Benin at Songhai Center library. Currently we installed Koha	
3.00.02.012 on Ubuntu 8.04 LTS.

I was successful using the manuals for installation. But when
the librarians are adding or editing an item in to the database, it will show us:

"Koha error

The following fatal error has occurred:

Can't call method "append_fields" on an undefined value at
/usr/local/share/perl/5.8.8/MARC/File/SAX.pm line 92.

Apache	Server version: Apache/2.2.8 (Ubuntu) Server built: Aug 18 2009 14:18:10
Koha	3.00.02.012
Koha DB	3.0002012
MySQL	mysql Ver 14.12 Distrib 5.0.51a, for debian-linux-gnu (i486) using
readline 5.2
OS	Linux sahel 2.6.24-24-server #1 SMP Tue Jul 7 20:21:17 UTC 2009 i686
Perl	5.008008 ''

Please any help!