Routes Learned from ASBR can't be summarized before advertising them to other peer
Detailed routes are learned in the Area while ASBR summary command is used but didn't summarize that routes
Please check the attached Diagram , R2 has two networks learned by Direct routing protocol , those routes will be advertised to other Peer using LSA Type 5 , if you are using ASBR Summary command , this command will be effective only when it configured in R2 ( ASBR) which has learned this routes .
ASBR Summary command can be used only to summarize routes learned in the ASBR Router and used also in the ASBR
ASBR Summary command summarize routes learned by ASBR and only it will be effective on ASBR