Hello NG

I work with ZCM 11 SP1a and the latest patches.
I created a Preboot Imaging Script

I started the preboot image restore and before the script was shown, I got
the following error:

Imaging Operation(s) assigned by
Elapsed time:L 00:00
Newer software is required. Please update your PXE files

ZENworks imaging failed with error:69
Novell ZENworks SID Changer for linux
Version -- Copyright 2007 -2011

Exiting: Computer has not been recently imaged

What could be the cause of this error?

Kind regards