DB2 hint 指定的Index用不到，请教！

cptwjyh

create index w2.PPANELDB_INDEX2 on w2.PPANELDB (chppstat);

select/*+ index(a PPANELDB_INDEX2) */ count(*)
from w2.ppaneldb a,
(select b.dpartno,b.dpngrp_id  from w2.ppngrp_dpn_ary b,w2.ppngrp c where b.dpngrp_id=c.dpngrp_id and c.mask_flg='Y' ) as e
where a.dpartno=e.dpartno and a.chppstat  in ('INPR','WAIT','WFPO')

上面的SQL用不到 Index PPANELDB_INDEX2，也尝试改为select/*+ index(a w2.PPANELDB_INDEX2) */   也不行，请教！