Can't Add ROWIDS to fragmented table

I fragmented a table, which worked well. But later on discovered there is a gnarly old 4GL program that uses the rowids field. No problem.... But when I try to add rowids with - ALTER TABLE sa_equipment ADD ROWIDS;- I get - 212: Cannot add index. 101: ISAM error: file is not open. Eh? That isn't helpful. Is there anyway to "unfragment" a table? The docs don't seem to mention that. IDS 10.00.UC4