Sounds interesting, but... Server Error in '/' Application. The INSERT statement conflicted with the FOREIGN KEY constraint "FK_tblArcadeGamePlays_tblReferals"

Sounds interesting, but... Server Error in '/' Application. The INSERT statement conflicted with the FOREIGN KEY constraint "FK_tblArcadeGamePlays_tblReferals". The conflict occurred in database "Scirra", table "dbo.tblReferals", column 'ID'. The statement has been terminated.