actualizacion de SQL server 2005 express a workgroup

Hola

Estamos intentando hacer una actualización in-place de sql Server Express
2005 a workgroup 2005. Como es una actualización la hacemos ejecutando
desde
línea de comandos "setup SKUUPGRADE=1". La instalación va OK hasta que
empieza a instalar los componentes y sale el siguiente error:

MSI (s) (E4:70) [15:35:13:500]: Product: Microsoft SQL Server 2005
Backward
compatibility -- Error 1706. An installation package for the product
Microsoft SQL Server 2005 Backward compatibility cannot be found. Try the
installation again using a valid copy of the installation package
'sqlserver2005_bc.msi'.

El resumen de la instalación os lo mando abajo

Muchas gracias en avance por vuestra ayuda


Microsoft SQL Server 2005 9.00.2047.00
==> OS Version : Microsoft Windows XP Professional Service Pack 2 (Build
2600)
Time : Fri Apr 20 15:28:17 2007

Machine : IOTSERVER
Product : Microsoft SQL Server Setup Support Files (English)
Product Version : 9.00.1399.06
Install : Successful
Log File : c:\Archivos de programa\Microsoft SQL Server\90\Setup
Bootstrap\LOG\Files\SQLSetup0011_IOTSERVER_SQLSupport_1.log
Machine : IOTSERVER
Product : Microsoft SQL Server Native Client
Product Version : 9.00.2047.00
Install : Successful
Log File : c:\Archivos de programa\Microsoft SQL Server\90\Setup
Bootstrap\LOG\Files\SQLSetup0011_IOTSERVER_SQLNCLI_1.log
Machine : IOTSERVER
Product : Microsoft Office 2003 Web Components
Product Version : 11.0.6558.0
Install : Successful
Log File : c:\Archivos de programa\Microsoft SQL Server\90\Setup
Bootstrap\LOG\Files\SQLSetup0011_IOTSERVER_OWC11_1.log
Machine : IOTSERVER
Product : SQL Server Backward-Compatibility Files
Error : An installation package for the product Microsoft SQL
Server 2005 Backward compatibility cannot be found. Try the installation
again using a valid copy of the installation package
'sqlserver2005_bc.msi'.
Machine : IOTSERVER
Product : Microsoft SQL Server 2005 Backward compatibility
Product Version : 8.05.1704
Install : Failed
Log File : c:\Archivos de programa\Microsoft SQL Server\90\Setup
Bootstrap\LOG\Files\SQLSetup0011_IOTSERVER_BackwardsCompat_1.log
Last Action : InstallFinalize
Error String : An installation package for the product Microsoft SQL
Server 2005 Backward compatibility cannot be found. Try the installation
again using a valid copy of the installation package
'sqlserver2005_bc.msi'.
Error Number : 1706
Machine : IOTSERVER
Product : MSXML 6.0 Parser (KB927977)
Product Version : 6.00.3890.0
Install : Successful
Log File : c:\Archivos de programa\Microsoft SQL Server\90\Setup
Bootstrap\LOG\Files\SQLSetup0011_IOTSERVER_MSXML6_1.log
Machine : IOTSERVER
Product : Microsoft SQL Server Setup Support Files (English)
Product Version : 9.00.1399.06
Install : Successful
Log File : c:\Archivos de programa\Microsoft SQL Server\90\Setup
Bootstrap\LOG\Files\SQLSetup0011_IOTSERVER_SQLSupport_2.log
Machine : IOTSERVER
Product : Microsoft Office 2003 Web Components
Product Version : 11.0.6558.0
Install : Successful
Log File : c:\Archivos de programa\Microsoft SQL Server\90\Setup
Bootstrap\LOG\Files\SQLSetup0011_IOTSERVER_OWC11_2.log
Machine : IOTSERVER
Product : Microsoft SQL Server Setup Support Files (English)
Product Version : 9.00.1399.06
Install : Successful
Log File : c:\Archivos de programa\Microsoft SQL Server\90\Setup
Bootstrap\LOG\Files\SQLSetup0011_IOTSERVER_SQLSupport_3.log
Machine : IOTSERVER
Product : Microsoft SQL Server Native Client
Product Version : 9.00.2047.00
Install : Successful
Log File : c:\Archivos de programa\Microsoft SQL Server\90\Setup
Bootstrap\LOG\Files\SQLSetup0011_IOTSERVER_SQLNCLI_2.log
Machine : IOTSERVER
Product : Microsoft Office 2003 Web Components
Product Version : 11.0.6558.0
Install : Successful
Log File : c:\Archivos de programa\Microsoft SQL Server\90\Setup
Bootstrap\LOG\Files\SQLSetup0011_IOTSERVER_OWC11_3.log
Machine : IOTSERVER
Product : Microsoft SQL Server VSS Writer
Product Version : 9.00.2047.00
Install : Successful
Log File : c:\Archivos de programa\Microsoft SQL Server\90\Setup
Bootstrap\LOG\Files\SQLSetup0011_IOTSERVER_SqlWriter_1.log
Machine : IOTSERVER
Product : MSXML 6.0 Parser (KB927977)
Product Version : 6.00.3890.0
Install : Successful
Log File : c:\Archivos de programa\Microsoft SQL Server\90\Setup
Bootstrap\LOG\Files\SQLSetup0011_IOTSERVER_MSXML6_2.log