how i can set as a PK_ID as Buisnesskey and use Changing Attribute in Slowly Changing Dimension in SSIS

hi

I have two different servers, but both have same set of DB and Table Schema.

Daily basis Source server Table have updated and new records. i need move only except cases from src to dest table.

here, table has 3 fields defined belod. In slowly Slowly Changing Dimension in SSIS i cloud not set PK_ID as buisness. pk_id is not display in key selection window and i tried both UserId_FK and UserGroupId_FK as buisnesskey but there no field in Slowly Changing Dimension columns window.

Column_name       Type    Key
PK_ID                   int          Identity(1,1) and Primary key
UserId_FK             varchar  (Not an unique value)
UserGroupId_FK    int         (Not an unique value)

Here how i can set as a PK_ID as Buisnesskey and use Changing Attribute

Regards

T Kumar