易魂网:VB里面连access报“对象变量或with块变量没有设置”怎么解决？详细点好么？我菜得可以~~

VB里面连access报“对象变量或with块变量没有设置”怎么解决？详细点好么？我菜得可以~~
这行： cmd.CommandText = " select houseid,posx,posy,posz From place Where boxid = 0 order by houseid,posz,posx,posy"
Set rs = cmd.Execute
If Not (rs.BOF Or rs.EOF) Then
'取最合适的空位
rs.MoveFirst
txtHouseid.Text = rs("houseid")
txtX.Text = rs("posx")
txtY.Text = rs("posy")
txtZ.Text = rs("posz")
模块里面是这样写的：
Option Explicit

Public conn As ADODB.Connection
Public cmd As ADODB.Command
Sub Main()
'建立数据库连接
Set conn = New ADODB.Connection
Set cmd = New ADODB.Command

conn.CursorLocation = adUseClient
cmd.CommandType = adCmdText
If conn.State <> adStateClosed Then
conn.Close
End If
conn.Open "driver={Microsoft Access Driver (*.mdb)};DBQ=" & App.Path & "C:\Documents and Settings\朱忠烈\桌面\DB1.mdb;uid=;PWD=;"

Set cmd.ActiveConnection = conn
Form1.Show
End Sub