getting not match date range result

hI,
i have two tables.

table a

sobid        begda_a                endda_a      owner

1063     1999-06-19         2010-11-30  No substan

table b

pernr          begda_b                     endda_b            plans  
1063      1976-06-18            1999-06-18      999999999    
1063      1999-06-19            2008-11-10     20078
1063      2008-11-11            2010-11-30     20078
1063      2010-12-01           999-12-31       999999999

i want ouput as below

999999999  1063 No substan  2010-12-01           999-12-31

i am trying to do

from  table a
right outer join table b
on a.sobid =b.perner
and endda_a not between begda_b  and endda_b
and b.endda='999-12-31'


not getting desire result