小女子又有问题了，请高手们帮帮忙，在线等待。。。。

我在编写一程序时，在一数据库菜单，单击数据库菜单下的业务员数据表，总出现以下错误：
“连接无法执行此操作，在此上下文中它可能被关闭或无效。”光标停留在rst.open"businessman",db,,,adcmdtable上该申明的都在模块中已作申明。
程序代码如下：
单击业务员数据表时的代码：
Private Sub mnubusinessman_Click()
currenttable = "businessman"
businessmantableopened = True
tablemenuenable
frmbusinessman.Show
End Sub
frmbusinessman窗体的载入程序如下：
showstatus ("数据管理－－ " & "务员数据表")
tablename = currenttable
Set rst = New ADODB.Recordset
rst.CursorType = adOpenStatic
rst.LockType = adLockPessimistic
rst.Open "businessman", db, , , adCmdTable
If rst.EOF Then
MsgBox "请添加业务员", , "业务员数据表"
txtid.Text = "b000000001"
cmdprevious.Enabled = False
cmdadd.Enabled = False
cmdsearch.Enabled = False
cmdsave.Enabled = False
cmdnext.Enabled = False
neworchange = True
Else
rst.MoveFirst
bshowfield rst
End If
End Sub
tablemenuenabler代码如下：
Public Sub tablemenuenable()
With frmmain
If businessmantableopened Then
!mnubusinessman.Enabled = False
Else
!mnubusinessman.Enabled = True
End If