Help for trigger

Question

i have two tables asset and feature.whenever i insert data into feature the trigger should automatically retrieve the asset_id from asset table and insert it.
these are the tables.
SQL> desc feature;
Name Null? Type
ASSET_ID NOT NULL NUMBER(11)
SITE_SECTION NOT NULL VARCHAR2(50)
HED NOT NULL VARCHAR2(256)
CONTENT_FORMAT NOT NULL VARCHAR2(256)
DEK VARCHAR2(256)
TOUT NOT NULL VARCHAR2(1024)
PUBLISH_DATE NOT NULL DATE
IMAGE_URL VARCHAR2(512)
FRAGMENT_PATH NOT NULL VARCHAR2(1024)
VPATH VARCHAR2(1024)
SQL> desc asset;
Name Null? Type
ASSET_ID NOT NULL NUMBER(11)
ASSET_TYPE_ID NOT NULL NUMBER(11)
CREATE_DT NOT NULL DATE
UPDATE_DT DATE
EXPR_DT DATE
TITLE VARCHAR2(256)
SR_SUMMARY VARCHAR2(1024)
CODEWORD VARCHAR2(1024)
VPATH NOT NULL VARCHAR2(1024)
AUTHOR VARCHAR2(100)
this is the trigger i have written
CREATE OR REPLACE TRIGGER INSERTFEATURE_ASSETID BEFORE INSERT ON
     FEATURE FOR EACH ROW
BEGIN
SELECT ASSET_ID into :NEW.ASSET_ID FROM ASSET WHERE ASSET_TYPE_ID = 15 AND VPATH
= :NEW.VPATH;
insert into feature(asset_id) values(:new.asset_id);
END;
when i am inserting data into feature with
insert into feature(site_section,hed,content_format,tout,publish_date,fragment_path,vpath)
values('asdf','acv','aaaa','aaaa',TO_DATE('06/06/1985','MM/DD/YYYY'),'qqqq','/even/more/paths');
it is saying no data found and error at the trigger in line 4;
where there is appropriate data in the asset table
SQL> select asset_id from asset where vpath='/some/other/path' and asset_type_id=15;
4
please help me.

Answer 1

thank you,
but if i have the trigger like this
CREATE OR REPLACE TRIGGER INSERTFEATURE_ASSETID BEFORE INSERT ON
     FEATURE FOR EACH ROW
BEGIN
SELECT ASSET_ID into :NEW.ASSET_ID FROM ASSET WHERE ASSET_TYPE_ID = 15 AND VPATH
= :NEW.VPATH;
END;
and
SQL> insert into feature(site_section,hed,content_format,tout,publish_date,fragment_path,vpath)
2 values('asdf','acv','aaaa','aaaa',TO_DATE('06/06/1985','MM/DD/YYYY'),'qqqq','/even/more/paths')
insert into feature(site_section,hed,content_format,tout,publish_date,fragment_path,vpath)
ERROR at line 1:
ORA-00001: unique constraint (BEDEV.PK_FEATURE_ASSET_ID) violated
this is the problem i am getting