erro ORA-0002298

olá a todos, tenho esta tabela z_reason :

CREATE TABLE "SAPSR3DB"."Z_REASON"

 (	"REASONCODE" VARCHAR2(3 CHAR) NOT NULL ENABLE,

	"REASONTEXT" VARCHAR2(100 CHAR),

	"REASONCAT" VARCHAR2(2 CHAR) NOT NULL ENABLE,

	"MACHINE" VARCHAR2(3 CHAR) NOT NULL ENABLE,

	"PLANT" VARCHAR2(4 CHAR) NOT NULL ENABLE,

	"LINENUMBER" VARCHAR2(8 CHAR) NOT NULL ENABLE,

 CONSTRAINT "Z_REASON_PK" PRIMARY KEY ("REASONCODE", "MACHINE", "PLANT", "LINENUMBER")

 USING INDEX PCTFREE 10 INITRANS 2 MAXTRANS 255 COMPUTE STATISTICS

 STORAGE(INITIAL 65536 NEXT 1048576 MINEXTENTS 1 MAXEXTENTS 2147483645

 PCTINCREASE 0 FREELISTS 1 FREELIST GROUPS 1 BUFFER_POOL DEFAULT)

 TABLESPACE "PSAPSR3DB" ENABLE,

 CONSTRAINT "Z_REASON_Z_MACHINE_FK1" FOREIGN KEY ("MACHINE", "PLANT", "LINENUMBER")

 REFERENCES "SAPSR3DB"."Z_MACHINE" ("MACHINE", "PLANT", "LINENUMBER") ENABLE,

 CONSTRAINT "Z_REASON_Z_PLANT_FK1" FOREIGN KEY ("PLANT")

 REFERENCES "SAPSR3DB"."Z_PLANT" ("PLANT") ENABLE,

 CONSTRAINT "Z_REASON_Z_LINE_FK1" FOREIGN KEY ("LINENUMBER", "PLANT")

 REFERENCES "SAPSR3DB"."Z_LINE" ("LINENUMBER", "PLANT") ENABLE,

 CONSTRAINT "Z_REASON_Z_REASON_CATEGOR_FK1" FOREIGN KEY ("REASONCAT", "LINENUMBER")

 REFERENCES "SAPSR3DB"."Z_REASON_CATEGORY" ("REASONCAT", "LINENUMBER") DISABLE

 ) PCTFREE 10 PCTUSED 40 INITRANS 1 MAXTRANS 255 NOCOMPRESS LOGGING

 STORAGE(INITIAL 65536 NEXT 1048576 MINEXTENTS 1 MAXEXTENTS 2147483645

 PCTINCREASE 0 FREELISTS 1 FREELIST GROUPS 1 BUFFER_POOL DEFAULT)

 TABLESPACE "PSAPSR3DB" ;

e esta z_reason_category

CREATE TABLE "SAPSR3DB"."Z_REASON_CATEGORY"

 (	"REASONCAT" VARCHAR2(2 CHAR) NOT NULL ENABLE,

	"REASONCATTEXT" VARCHAR2(30 CHAR),

	"LINENUMBER" VARCHAR2(8 CHAR) NOT NULL ENABLE,

	"FLAG" NUMBER,

 CONSTRAINT "Z_REASON_CATEGORY_PK" PRIMARY KEY ("REASONCAT", "LINENUMBER")

 USING INDEX PCTFREE 10 INITRANS 2 MAXTRANS 255 COMPUTE STATISTICS

 STORAGE(INITIAL 65536 NEXT 1048576 MINEXTENTS 1 MAXEXTENTS 2147483645

 PCTINCREASE 0 FREELISTS 1 FREELIST GROUPS 1 BUFFER_POOL DEFAULT)

 TABLESPACE "PSAPSR3DB" ENABLE

 ) PCTFREE 10 PCTUSED 40 INITRANS 1 MAXTRANS 255 NOCOMPRESS LOGGING

 STORAGE(INITIAL 65536 NEXT 1048576 MINEXTENTS 1 MAXEXTENTS 2147483645

 PCTINCREASE 0 FREELISTS 1 FREELIST GROUPS 1 BUFFER_POOL DEFAULT)

 TABLESPACE "PSAPSR3DB" ;

mas quando tento por a foreign key...(o texto está sublinhado) em enable dá-me o erro ORA-02298...

alguém me pode dizer qual a causa do erro e a posssivel solução

abraço e obrigado desde já pela ajuda

matinha