Error: there is no such archive

I have created a backup job with the following options (GUI in German):
- Typ: Komplett
- Format: 7-Zip
- Kompressionslevel: Keine (-> none)
- Sonstiges: Passwort, Test After Creation
- no rules
- Backup source is a complete directory on a memory stick
- Backup destination in an existing directory on the computer

As soon as I run this job I get the following output in the progress window:

10:27:21 Toucan 3.0.3
Date: 2010-12-03
Computer Name: ((snip))

Operating System: Windows XP (build 2600, Service Pack 3)
Erstelle Liste der Dateien, dies kann eine Weile dauern.

7-Zip 9.13 beta Copyright (c) 1999-2010 Igor Pavlov 2010-04-15

10:27:41 Error:
there is no such archive

Elapsed: 00:00:20

What am I doing wrong? If I do the same backup with the Typ: Differentiell then it works and I get the following message in the progress window:

10:39:18 Toucan 3.0.3
Date: 2010-12-03
Computer Name: ((snip))
Operating System: Windows XP (build 2600, Service Pack 3)

Erstelle Liste der Dateien, dies kann eine Weile dauern.

7-Zip 9.13 beta Copyright (c) 1999-2010 Igor Pavlov 2010-04-15

Scanning

Creating archive C:\((snip))\2010-12-03-10-39.7z

Compressing ((snip))\((snip)).ini

Compressing ((snip))\((snip)).exe

Compressing ((snip))\((snip)).exe

Compressing ((snip))\((snip)).dll

Compressing ((snip))\((snip)).dll

Compressing ((snip))\((snip)).inf
Compressing ((snip))\((snip)).res
Compressing ((snip))\((snip)).res
Compressing ((snip))\((snip)).sle

Everything is Ok

7-Zip 9.13 beta Copyright (c) 1999-2010 Igor Pavlov 2010-04-15

Processing archive: C:\((snip))\2010-12-03-10-39.7z

and the backup operation seems to complete successfully. To my understanding the full backup should exactly work the same as the differentiell, just the backuped information is everything not just the difference since the last backup.

Any suggestions what I am doing wrong, or is it a bug in the software?

P.S. For confidentiality reasons I have replaced all path and filenames by ((snip))