Hi Julien and Jayasimha
Is you SU24 data in the child system and synched? I only ask this as I saw similar post and some notes that referred to authorisation maintenance issues due to SU24 data not imported in child system properly. Here's one of the threads as an example:
http://scn.sap.com/thread/2105640
If it's not this, you both have reported same issue - what SP are you on? There may be a need to raise message with SAP?
Regards
Colleen