请问一下，为什么我在表单写入时，两项就可以，再多两项就不行了。怎么办

<%
dim exp_title,exp_people
if request("exp_title")="" then
    response.write "<script language=JavaScript>" & chr(13) & "alert('请输入实验名！');" & "history.back()" & "</script>"
    Response.End
end if
if request("exp_people")="" then
    response.write "<script language=JavaScript>" & chr(13) & "alert('请输入实验人！');" & "history.back()" & "</script>"
    Response.End
end if

exp_title=request("exp_title")
exp_people=request("exp_people")
dim sql
dim rs
dim conn
set rs=server.createobject("adodb.recordset")
conn = "DBQ=" + server.mappath("baogao.mdb") + ";DefaultDir=;DRIVER={Microsoft Access Driver (*.mdb)};"
sql="insert into baogao(exp_title,exp_people) values('"&exp_title&"','"&exp_people&"')"
rs.Open sql,conn,3,3
Response.Write "记录添加成功!"
%>
以上可以写入数据库
<%
dim exp_title,exp_people,student_number,exp_teacher
if request("exp_title")="" then
    response.write "<script language=JavaScript>" & chr(13) & "alert('请输入实验名！');" & "history.back()" & "</script>"
    Response.End
end if
if request("student_number")="" then
    response.write "<script language=JavaScript>" & chr(13) & "alert('请输入学号！');" & "history.back()" & "</script>"
    Response.End
end if

exp_title=request("exp_title")
exp_people=request("exp_people")
student_number=request("student_number")
exp_teacher=request("exp_teacher")

dim sql
dim rs
dim conn
set rs=server.createobject("adodb.recordset")
conn = "DBQ=" + server.mappath("baogao.mdb") + ";DefaultDir=;DRIVER={Microsoft Access Driver (*.mdb)};"
sql="insert into baogao(exp_title,exp_people，exp_people，student_number，exp_teacher) values('"&exp_title&"','"&exp_people&"'，'"&student_number&"，'"&exp_teacher&"'')"
rs.Open sql,conn,3,3
Response.Write "记录添加成功!"
%>
这个就不可以了，