SQL & PL/SQL

select * from (select
d.ecev_tag ecev_tag,
a.digp_tag entity_owner ,
c.digp_tag task_owner,
c.tk_tag task_tag,
c.due_date,
c.narrative
from enow a,
entl b,
tk c,
ecev d ,
(SELECT distinct parent_digp_tag
from
(
SELECT parent_digp_tag, child_digp_tag
FROM dghi
START WITH child_digp_tag=100
CONNECT BY PRIOR parent_digp_tag= child_digp_Tag)) e
where ( a.DIGP_TAG=100 or c.digp_tag=100 or a.digp_tag=e.parent_digp_tag or c.digp_tag=e.parent_digp_tag)
and a.entity_tag=b.entity_tag(+)
and b.tk_tag=c.tk_tag(+)
and a.entity_tag=d.ecev_tag
and a.cept_tag=c.cept_tag(+)

I am getting..
and b.tk_tag=c.tk_tag(+)
*
ERROR at line 21:
ORA-01417: a table may be outer joined to at most one other table


Thanks
Ram