Cause: The block's DML Array Size property value is greater than 1, but no items have the Primary Key property set to Yes and one of the following is true:
1. The key mode for the block is either UPDATEABLE_PRIMARY_KEY or NON_UPDATEABLE_PRIMARY_KEY.
2. The datasource to which you are connected does not support UNIQUE key mode.
Action: Do one of the following:
1. Specify a primary key for the data block by setting the Primary Key property value to Yes for one or more items.
2. Set the data block's DML Array Size property to 1.