MDT 2012 fails to run command line in TS

I'm trying to run a VBscript (as another user) in my Task Sequence, but it fails. (I'm deploying Windows 7 x64 with the Standard Client Task Sequence-template).

• When running the script manually, outside the MDT environment, it works flawless.
• Also creating a custom Task Sequence with only the 'Run Command Line'-step, running my VBS (as a service account), works great!
• Tried this workaround: Run command line as domain user – Incorrect Function Error. Without success.

I'm using a 'Run Command Line' step, with this as command line;

cscript.exe "%deployroot%\scripts\MyScript.vbs"

The script is copied to the deployment share, in the scripts-folder. I'm sure the syntax is correct, because the Custom Task Sequence does work.

Error message after deployment:

Litetouch deployment failed, Return Code = -2147467259 0x80004005 Failed to run the action: Add domain user based on the current computername. Incorrect function. (Error: 00000001; Source: Windows) The execution of the group (State Restore) has failed
 and the execution has been aborted. An action failed. Operation aborted (Error: 80004004; Source: Windows) Failed to run the last action: Add domain user based on the current computername. Execution of task sequence failed. Incorrect function. (Error: 00000001;
 Source: Windows) Task Sequence Engine failed! Code: enExecutionFail Task sequence execution failed with error code 80004005 Error Task Sequence Manager failed to execute task sequence. Code 0x80004005

smsts.log;

Failed to run the action: Add domain user based on the current computername. Incorrect function. (Error: 00000001; Source: Windows)

The execution of the group (State Restore) has failed and the execution has been aborted. An action failed.Operation aborted (Error: 80004004; Source: Windows)

Failed to run the last action: Add domain user based on the current computername. Execution of task sequence failed.Incorrect function. (Error: 00000001; Source: Windows)

Task Sequence Engine failed! Code: enExecutionFail

Task sequence execution failed with error code 80004005

Error Task Sequence Manager failed to execute task sequence. Code 0x80004005

.

Because the scripts works manually and in a custom Task Sequence, I don't understand what I'm doing wrong. Can someone help me out please?