ORA-00904 Error (need help)

I am receiving a PL/SQL: ORA-00904: "DOCREF": invalid identifier am not sure why.  Can someone provide guidance?
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This is my source code -

CREATE OR REPLACE PROCEDURE Sp_Sel_Xmldoc(iNODEID IN NUMBER, iDOCTYPE IN VARCHAR2, iDOCREF IN NUMBER,
         oxmldata OUT sys.XMLTYPE)

AS

V_NODEID NUMBER(10);
V_DOCTYPE VARCHAR2(20);
V_DOCREF NUMBER(10);
V_XMLDATA  sys.XMLTYPE;

BEGIN

V_NODEID             := iNODEID;
V_DOCTYPE          := iDOCTYPE;
V_DOCREF            := iDOCREF;

SELECT XMLDOC INTO (V_XMLDATA)
FROM NODALXML

WHERE nodeid = V_NODEID
AND doctype = V_DOCTYPE
AND docref = V_DOCREF;

END;
/

The oracle table looks like this -

CREATE TABLE PRISM.NODALXML
(
  NODALXML_PK  NUMBER(10),
  NODEID       NUMBER(10),
  DOCTYPE      VARCHAR2(20 BYTE),
  DOCREF       NUMBER(10),
  XMLDOC       SYS.XMLTYPE
)

Thanks.