now, the code change into this:

WITH THISFORM.DATAENVIRONMENT
.ADDOBJECT('CURSOR1','Cursor')
.CURSOR1.CURSORSOURCE = CDX_DBF + 'SODETAIL'
.CURSOR1.ALIAS = 'CURSOR1'

.ADDOBJECT('CURSOR2','Cursor')
.Cursor2.CURSORSOURCE = CDX_DBF + 'SOHEAD'
.CURSOR2.ALIAS = 'CURSOR2'

.ADDOBJECT('CURSOR3','Cursor')
.Cursor3.CURSORSOURCE = CDX_DBF + 'ITEMMSTR'
.CURSOR3.ALIAS = 'ITEMMSTR'

.ADDOBJECT('CURSOR4','Cursor')
.Cursor4.CURSORSOURCE = CDX_DBF + 'CUSTOMER'
.CURSOR4.ALIAS = 'CUSTOMER'
ENDWITH

THISFORM.DATAENVIRONMENT.OPENTABLES()

*********

With Thisform.DET_GRD
.recordsourcetype = 1 && 1 Alias
.recordsource = 'CURSOR1'
EndWith

no any error message prompt out, but the grid still cannot display any data~