jsp 아이디 값이 null값으로 나와요ㅜㅜ (아이디찾기)

간단한 소스 올려드릴게요...
제가 어떤부분이 빠졌는가잘못됐나 봐주십쇼..ㅜㅜ
이름과 주민등록번호를 이용하여 디비에 저장되어있는 아이디를 얻어오는겁니다..ㅜㅜ----------------------idpw_search.jsp----------------------

%@ page language=java contenttype=text/html; charset=euc-kr
pageencoding=euc-kr import=java.sql.*,java.sql.timestamp,com.mem.*%

html
head

titleinsert title here/title
/head

script src=member/check.js language=javascript
/script

%

httpsession ses = request.getsession();
string mb_id=(string)ses.getattribute(pok);

memberdao db = new memberdao();

%

body
table width=861 border=0 cellpadding=0 cellspacing=0
tr
td height=60 valign=bottom background=common/images/c_catback.gifimg src=images/member/title_join.gif/td
/tr
tr
td /td
/tr
/table
brbrbr
!-- 아이디/패스워드 찾기 폼 --
form name=idpwform method=post action=index.jsp?content=member/idpw_pro.jsp
table border=0 cellpadding=0 cellspacing=0
tr
td height=100

table border=0 cellpadding=0 cellspacing=0
tr
td height=30 align=rightimg src=images/member/login_img04.jpg/td
td align=leftinput type=text name=mb_name size=12 maxlength=30/td
td /td
/tr
tr
tdimg src=images/member/login_img05.jpg/td
tdinput type=text name=jumin1 size=12 maxlength=6 - input type=text name=jumin2 size=12 maxlength=7/td
tdimg src=images/member/icon_go.jpg border=0 onclick=idpwcheck()/td
/tr
/table

/td
/tr
tr
tdimg src=images/member/login_img01.jpg/td
/tr
tr
td height=70a href=index.jsp?content=member/join_form.jspimg src=images/member/icon_joingo.jpg border=0/a
a href=img src=images/member/icon_idpwgo.jpg border=0 /a/td
/tr
/table
/form
!----
brbrbrbr
/body
/html

-------------------------idpw_pro.jsp---------------------------------%@ page language=java contenttype=text/html; charset=euc-kr
pageencoding=euc-kr import=java.sql.*,java.sql.timestamp,com.mem.*%

%
request.setcharacterencoding(euc-kr);
%
html
head
titleinsert title here/title
/head

!-- 객체 생성을 의미--
jsp:usebean id=dto class=com.mem.memberdto scope=session /
jsp:setproperty name=dto property=*/
%

string mb_name = request.getparameter(mb_name);
dto.setmb_name(mb_name);
//주번 넣기

string jumin1 = request.getparameter(jumin1);
string jumin2 = request.getparameter(jumin2);

string mb_jumin = jumin1 +-+ jumin2;
dto.setmb_jumin(mb_jumin);

httpsession ses = request.getsession();
string mb_id=(string)ses.getattribute(pok);

dto.setmb_id(mb_id);

memberdao db = new memberdao();%

body

!-- 서브 타이틀 부분 --
table width=861 border=0 cellpadding=0 cellspacing=0
tr
td height=60 valign=bottom background=common/images/c_catback.gifimg src=images/member/title_join.gif/td
/tr
tr
td /td
/tr
/table
!----
%

int a = db.idpwselect(mb_name,mb_jumin);
if(a == 1) {
%

!-- 완료내용 --
table width=500 border=0 cellpadding=0 cellspacing=10
tr
td align=left height=80span class=text_pointcenter고객님의 아이디는 %=dto.getmb_id()% 입니다./center/span.br
/td
/tr
tr
tda href=index.jsp?content=member/login_form.jspimg src=images/member/btn_submit.gif border=0/a/td
/tr
/table

%
}else if(a == 0) {
%
bsp;script language=javascript
alert(이름과 주민등록번호가 일치하지 않습니다.)
history.go(-1);
/script
%
}
%
/body
/html---------------------memberdao.java 일부분 --------------//////////////////////아이디 비밀번호 찾기//////////////////////////////////////////

public int idpwselect(string mb_name,string mb_jumin) {

memberdto dto = new memberdto();

int re=0;

try{
conn = this.getconnection();
string sql =select mb_id from member where mb_name=? and mb_jumin=?;
system.out.println(sql=+sql);

pstmt = conn.preparestatement(sql);
pstmt.setstring(1,mb_name);
pstmt.setstring(2,mb_jumin);

rs = pstmt.executequery();if(rs.next()) {dto = new memberdto();
dto.setmb_id(rs.getstring(mb_id));

re = pstmt.executeupdate();

}

}catch (sqlexception e) {
system.out.println(delete error :+e);
e.printstacktrace();
}finally {
this.dbclose();
}
return re;
}