Add a day to a date in Progress OpenEdge db query

I am looking for a way to increment a date value by one day in Progress OpenEdge DB query. I am using the OpenEdge SQL-92 query engine rather than the ABL (4gl) engine. Something similar to how one might do it for a SQL server query would be ideal: --first attempt SELECT DateAdd("d",1,EffDate) FROM pub.pv_currrates --another attempt does not work SELECT ADD-INTERVAL(b.BillDate, days, 1) AS one_day_back ... UPDATE: I found this add-interval function, but we can't seem to get it to work correctly.