Diagnosis
The budget structure whose validity you have chosen to extend, containsone or more budget units whose validity has already been extended. Thebudget period that you want to extend the structure's validity into hasthe same start date as the budget periods of the budget units whosevalidity has already been extended.
You can only extend the validity of a budget structure if all itsbudget units do not exist in the chosen validity extension period.

Procedure
If the budget structure is still in the status planned in the period inwhich it has been extende, then you can delete it and then extend itinto the budget period of your choice.