Message type: E = Error
Message class:  KZ - Cost Object Repetitive Mfg / Process Mfg 
Message number: 134
Message text: No cost element group was selected
You cancelled the selection of the cost element groups. The row
structure of the report is specified via a <GL:cost_element_group>cost
element group</>. If you do not select a cost element group, the system
proposes one for the report.
The system issues an error message and will not allow you to continue with this transaction until the error is resolved.
If you do not wish to use the cost element group proposed, select
<LS>Selection -> Cost element group</> again.
Error message extract from SAP system. Copyright SAP SE.
The SAP error message KZ134 ("No cost element group was selected") typically occurs in the context of cost accounting or when working with cost element reports. This error indicates that the system could not find a cost element group that meets the criteria specified in the transaction or report you are trying to execute.
Cause:
Missing Cost Element Group: The cost element group you are trying to use may not exist in the system.
Incorrect Configuration: The configuration for cost element groups may not be set up correctly in the system.
Selection Criteria: The selection criteria you are using in your report or transaction may not match any existing cost element groups.
Authorization Issues: There may be authorization issues preventing you from accessing the cost element groups.
Solution:
Check Cost Element Groups:
Go to the transaction code OKB2 (Cost Element Group) to check if the cost element group you are trying to use exists.
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