It strikes me that your field modacad.key4 is not actually logical, as you have the clause: "WHERE modacad.key4<>'TECHNICAL'" and that's the one you're binding to the checkbox in the grid. Did you add it to your source table on advice in the previous thread? I don't know if key4 is the field you want to be checked but, if you just want a check field for data selection then I suggest:

SELECT key3, key4, moc011, mochk009, .F. as MYCHECKFIELD ;
FROM "U:\Data\modacad.dbf" ;
WHERE modacad.key4<>'TECHNICAL' ;
ORDER BY key3 ;
INTO CURSOR result readwrite

and bind MYCHECKFIELD to the checkbox.