node add form == hook form alter not effective ?

dear all friends.

one content type: aaa,
then there is a aaa_node_form insde node/add/aaa's page (suppose)
then I use seven_form_alter to change this form,
i delete the default language and language neutral option.
values are reset or deleted,
but display is not changing.

can some one tell us and make it clear.

thanks.