SSRS AX 2012 Error: Element ':PurchPurchaseOrder.Parameters.IsPurchConfirmationRequestJournal' has already been defined. To correct this, rename one or more of the model elements so that they have a unique name.

When we customize PurchPurchaseOrderReport to add a field on PurchPurchaseOrder Dataset in AOT and refresh dataset in Visual Studio.

We will get following error message:
Element':PurchPurchaseOrder.Parameters.IsPurchConfirmationRequestJournal’ has already been defined. To correct this, rename one or more of the model elements so that they have a unique name.


This is very common error and we can fix it by doing following steps: 

1. Prior to refreshing Dataset, we have to rename the parameter IsPurchConfirmationRequestJournal to IsPurchConfirmationRequestJournalDelete
2. Change the following properties:
   1. nullable – True
   2. allow blank – True
3. Now refresh the dataset you should not see any errors and a new parameter IsPurchConfirmationRequestJournal will be created. Now set the below properties of new parameter:
   1. allow blank – True
   2. Nullable – True
4. Once the properties are set, now delete the parameter ‘IsPurchConfirmationRequestJournalDelete’.
5. Rebuild the solution and deploy the report.