未结束的字符串常量

if request("action")="login" then
username=request("username")
password=request("password")
set rs=server.CreateObject("adodb.recordset")
sql="select * from admin where username='"&username&"' and password='"&password&"'"
rs.open sql,conn,3,3
if rs.eof then
response.Write("用户名和密码不匹配")
else
session("username")=rs("username")
session("quanxian")=rs("quanxian")
response.Redirect "loginok.asp"

错误类型：
Microsoft VBScript 编译器错误 (0x800A0409)
未结束的字符串常量
/li/shangwu/admin/login.asp, line 50, column 31
response.Write("鐢ㄦ埛鍚嶅拰瀵嗙爜涓嶅尮閰?)
------------------------------^
这是什么原因呢 哪个高手解答下

定义Sql语句那行改成如下..

sql="select * from admin where username='"&username&"' and password='"&password&'"

程序不完整！ if request("action")="login" then username=request("username") password=request("password") set rs=server.CreateObject("adodb.recordset") sql="select * from admin where username='"&username&"' and password='"&password&"'" rs.open sql,conn,3,3 if rs.eof then response.Write("用户名和密码不匹配") else session("username")=rs("username") session("quanxian")=rs("quanxian") response.Redirect "loginok.asp" end if end if //少两个end if