Error when using SCD Type 2 Loader with SAS DI Studio

[WorkingMan]

I am a SAS Developer and I am using SAS Data Integration Studio to build ETL jobs. I am facing an issue with SCD Type 2 Loader whereby all business key, changing columns, date, generate columns are properly set but is hitting the error below:

ERROR: no keys variable have been defined for file ACCOUNT_DIM

Upon googling, I think this has something to do with index and key. Currently, this SCD Type 2 Loader will generate "ACCOUNT_SK" but at the same time, this particular column in ACCOUNT_DIM table has index and key set to "ACCOUNT_SK". Is there any issue of conflict if a column is set as generate and index + key at the same time? If no, what could be the cause of this?