SQL query Help - result not correct

ORACLE DB: 11.2.0.3

QUESTION: I am trying to join two table and not getting expected result.

Expected Result:

       

DG_NAME	TOTAL_SPACE	TIER_1	TIER_2	TIER_3	SNAP_DATE	REQ_TIERS	DISKGROUP_PURPOSE
DATA_00	5242880	172400	4075800	765584	9/5/2014	ALL	UNDO,SYSTEM
Data_03	6291456	200	143074	5556536	9/5/2014	SLC	Application A only
DATA_04	4194304	161740	3158140	1035372	9/5/2014	3RD TIER	Project B and C
DATA_05	1048576	522594	0	0	9/5/2014	SLC MLC	Project J and X

*********** Table info. ****

TABLE 1:

SAN_STORAGE_SNAPSHOT

(

  DG_NAME        VARCHAR2(20 BYTE),

  LUN_SIZE       NUMBER(10),

  TIER_1         NUMBER(10),

  TIER_2         NUMBER(10),

  TIER_3         NUMBER(10),

  SNAP_DATE      DATE,

  )

DATA:

DG_NAME    LUN_SIZE    TIER_1    TIER_2    TIER_3    SNAP_DATE

Data_00_0000    2097152    69804    1645712    304438    9/5/2014

Data_00_0001    2097152    69588    1644456    305702    9/5/2014

Data_00_0002    1048576    33008    785632    155444    9/5/2014

Data_03_0000    2097152    58    48334    2039852    9/5/2014

Data_03_0001    2097152    36    46736    2041480    9/5/2014

Data_03_0002    2097152    106    48004    1475204    9/5/2014

Data_04_0000    2097152    80416    1565834    530924    9/5/2014

Data_04_0001    2097152    81324    1592306    504448    9/5/2014

Data_05_0000    1048576    522594    0    0    9/5/2014

TABLE 2:

DISK_GROUP_PURPOSE

(

  DISKGROUP_NAME     VARCHAR2(20 BYTE),