I have a form with a method called zallownew.
This method must return true before a new record can be added to the main table in the DE.

intermittenly I am getting this error, usually when the plays table is empty or has only a few records:
WARNING UNABLE TO COMMIT CHANGES FOR PLAYS-INSERT TRIGGER FAILED.

ERROR #1539 in Zallownew line 9 workarea 0 trigger failed

Line 9 is "GO TOP" zallownew looks like this:

*****************************
** set maximum records in demo mode
LOCAL lcConfirm, lnplays, lnMaxplays, lnREcno
lnMaxplays=20

**get the number of valid plays
lnplays=0
SELECT plays
GO top
lnRecNo=RECNO()
SCAN FOR !DELETED() AND plays.gamenum==games.gamenum
	lnplays=lnplays+1
ENDSCAN

**return serial number mode
lcConfirm=thisform.zserialconfirm('PLAYS')
*lcConfirm='FULL' &&Full version test
SELECT plays
*GO lnRecNo
*thisform.Refresh()

DO case
	CASE lcConfirm=='DEMO'	&&standard demo mode
		IF lnplays>=lnMaxplays
			thisform.omessage.warning(PROPER('This demo version has exceeded the allowable number of plays'))
			m.gostatemanager.openform('utilregister.scx')
			RETURN .f.	
		ELSE
			RETURN .t.
		endif
	CASE lcConfirm!='DEMO' AND lcConfirm!='FULL'	&&extended demo mode
		lnMaxplays=VAL(lcConfirm)
		IF lnplays>=lnMaxplays
			thisform.omessage.warning(PROPER('This demo version has exceeded the allowable number of plays'))
			m.gostatemanager.openform('utilregister.scx')
			RETURN .f.	
		ELSE
			RETURN .t.
		endif		
	CASE lcConfirm=='FULL'	&&full mode
		RETURN .t.
	OTHERWISE
		m.gostatemanager.openform('utilregister.scx')
		RETURN .f.
endcase

The insert trigger is the system created RI:

********************************************************************************
** "Referential integrity insert trigger for" plays
PROCEDURE __RI_INSERT_plays
LOCAL llRetVal
llRetVal = .t.
PRIVATE pcParentDBF,pnParentRec,pcChildDBF,pnChildRec,pcParentID,pcChildID
PRIVATE pcParentExpr,pcChildExpr
STORE "" TO pcParentDBF,pcChildDBF,pcParentID,pcChildID,pcParentExpr,pcChildExpr
STORE 0 TO pnParentRec,pnChildRec
IF _triggerlevel=1
  BEGIN TRANSACTION
  PRIVATE pcRIcursors,pcRIwkareas,pcRIolderror,pnerror,;
  pcOldDele,pcOldExact,pcOldTalk,pcOldCompat,PcOldDBC
  pcOldTalk=SET("TALK")
  SET TALK OFF
  pcOldDele=SET("DELETED")
  pcOldExact=SET("EXACT")
  pcOldCompat=SET("COMPATIBLE")
  SET COMPATIBLE OFF
  SET DELETED ON
  SET EXACT OFF
  pcRIcursors=""
  pcRIwkareas=""
  pcRIolderror=ON("error")
  pnerror=0
  ON ERROR pnerror=rierror(ERROR(),message(),message(1),program())
  IF TYPE('gaErrors(1)')<>"U"
    release gaErrors
  ENDIF
  PUBLIC gaErrors(1,12)
  pcOldDBC=DBC()
  SET DATA TO ("COMPUSPORTS")
ENDIF first trigger
LOCAL lcChildID && child's value to be sought in parent
LOCAL lcParentWkArea && parentwork area handle returned by riopen
LOCAL lcChildWkArea && child's work area
LOCAL lcStartArea
lcStartArea=select()
llRetVal=.t.
lcChildWkArea=SELECT()
SELECT (lcChildWkArea)
lcChildID=GAMENUM
pcChildDBF=dbf(lcChildWkArea)
pnChildRec=recno(lcChildWkArea)
pcChildID=lcChildID
pcChildExpr="GAMENUM"
lcParentWkArea=riopen("games","gamenum")
IF lcParentWkArea<=0
  IF _triggerlevel=1
    DO riend WITH .F.
  ENDIF at the end of the highest trigger level
  SELECT (lcStartArea)
  RETURN .F.
ENDIF not able to open the child work area
pcParentDBF=dbf(lcParentWkArea)
llRetVal=SEEK(lcChildID,lcParentWkArea)
pnParentRec=recno(lcParentWkArea)
=rireuse("games",lcParentWkArea)
IF NOT llRetVal
  DO rierror with -1,"Insert restrict rule violated.","",""
  IF _triggerlevel=1
    DO riend WITH llRetVal
  ENDIF at the end of the highest trigger level
  SELECT (lcStartArea)
  RETURN llRetVal
ENDIF
IF _triggerlevel=1
  do riend with llRetVal
ENDIF at the end of the highest trigger level
SELECT (lcStartArea)
RETURN llRetVal
** "End of Referential integrity insert trigger for" plays
********************************************************************************