adprep /domainprep error 0x208d

Hi,

I need to replace my current DC with new one and I want to degrade current DC to backup (second DC).

My current DC is:
- Windows 2003 SP2 x86, language: PL
- Domain functional Level: 2003
- Forest functional level: 2003
- AD schema version: 47

My new DC is:
- Windows 2008 R2 SP1 x64, language: EN

My plan is: promote new DC as additional DC for an existing DC, transfer FSMO, DHCP, etc...

But during promotion I have an error:

On current DC I executed adprep32.exe (from install CD of Windows 2008 R2) with /domainprep option but I had errors:

Adprep was unable to modify the security descriptor on object CN=IP Security,CN=System,DC=main,DC=domain,DC=local.

[Status/Consequence] 
ADPREP was unable to merge the existing security descriptor with the new access control entry (ACE).


Adprep encountered an LDAP error. 

Error code: 0x20. Server extended error code: 0x208d, Server error message: 0000208D: NameErr: DSID-031001CD, problem 2001 (NO_OBJECT), data 0, best match of:
	'CN=System,DC=main,DC=domain,DC=local'
.

Adprep was unable to update domain information. 

[Status/Consequence]
Adprep requires access to existing domain-wide information from the infrastructure master in order to complete this operation.

Could this be due to differed language versions on current DC and new DC?