Hi BPC,
Please do following and you should have exact idea as to which authorization object is missing in your user id.
1. Run the process chain
2. Check SU53 in your BW system for the user who is running the process chain - You can check the authorizations for other users too from top menu (Authorization Values -> Other User -> Execute)
3. Do same activity in source system too.
With this you will get better idea about missing authorization.
Also try to do below:
1. Goto the Planning View of the Process Chain.
2. Goto "Process chain" >>> Display/Change.
3. Goto "Process chain" >>> Attributes >>> Execution User >>> tick "Current User".
For authrizations contact your basis team as experts suggest.
Thanks
Amit