问了三天的问题了谁能帮我解决下啊

这个是我数据源的模块代码,数据源连接正常

Public fMainForm As frmMain
Public UserName As String
Public gintMode As Integer
Public flagEdit As Boolean

Sub Main()
    Dim fLogin As New frmLogin
    fLogin.Show vbModal
    If Not fLogin.OK Then
        'Login Failed so exit app
        End
    End If
    Unload fLogin

    Set fMainForm = New frmMain
    fMainForm.Show
End Sub
Public Function ConnectString() _
   As String
'returns a DB ConnectString
   ConnectString = "DSN=ecardinfo.dsn;UID=sa;PWD=admin"
End Function
Public Function ExecuteSQL(ByVal sql _
   As String, msgstring As String) _
   As ADODB.Recordset
'executes SQL and returns Recordset
   Dim cnn As ADODB.Connection
   Dim rst As ADODB.Recordset
   Dim sTokens() As String

   On Error GoTo ExecuteSQL_Error

   sTokens = Split(sql)
   Set cnn = New ADODB.Connection
   cnn.Open ConnectString
   If InStr("INSERT,DELETE,UPDATE", _
      UCase$(sTokens(0))) Then
      cnn.Execute sql
      msgstring = sTokens(0) & _
         " query successful"
   Else
      Set rst = New ADODB.Recordset
      rst.Open Trim$(sql), cnn, _
         adOpenKeyset, _
         adLockOptimistic
      'rst.MoveLast     'get RecordCount
      Set ExecuteSQL = rst
      msgstring = "查询到" & rst.RecordCount & _
         " 条记录 "
   End If
ExecuteSQL_Exit:
   Set rst = Nothing
   Set cnn = Nothing
   Exit Function

ExecuteSQL_Error:
   msgstring = "查询错误: " & _
      Err.Description
   Resume ExecuteSQL_Exit
End Function

Public Function Testtxt(txt As String) As Boolean
    If Trim(txt) = "" Then
        Testtxt = False
    Else
        Testtxt = True
    End If
End Function

Public Sub EnterToTab(Keyasc As Integer)
    If Keyasc = 13 Then
        SendKeys "{TAB}"
    End If
End Sub
----------
这个是程序代码执行时提示错误
If mrc.EOF = True Then出现“实时错误‘91’对象变量或WITH 块变量未设置”
程序代码
--------
Option Explicit
Private Declare Function GetUserName Lib "advapi32.dll" Alias "GetUserNameA" (ByVal lpbuffer As String, nSize As Long) As Long

Public OK As Boolean
'记录确定次数
Dim miCount As Integer
Private Sub Form_Load()
    Dim sBuffer As String
    Dim lSize As Long

    sBuffer = Space$(255)
    lSize = Len(sBuffer)
    Call GetUserName(sBuffer, lSize)
    If lSize > 0 Then
        txtUserName.Text = ""

    Else
        txtUserName.Text = vbNullString
    End If

    OK = False
    miCount = 0
End Sub

Private Sub cmdCancel_Click()
    OK = False
    Me.Hide
End Sub

Private Sub cmdOK_Click()
    Dim txtSQL As String
    Dim mrc As ADODB.Recordset
    Dim MsgText As String

    UserName = ""
    If Trim(txtUserName.Text) = "" Then
        MsgBox "没有这个用户，请重新输入用户名！", vbOKOnly + vbExclamation, "警告"
        txtUserName.SetFocus
    Else
        txtSQL = "select * from user_Info where user_ID = '" & txtUserName.Text & "'"
        Set mrc = ExecuteSQL(txtSQL, MsgText)
        If mrc.EOF = True Then
            MsgBox "没有这个用户，请重新输入用户名!", vbOKOnly + vbExclamation, "警告"
            txtUserName.SetFocus
        Else
            If Trim(mrc.Fields(1)) = Trim(txtPassword.Text) Then
                OK = True
                mrc.Close
                Me.Hide
                UserName = Trim(txtUserName.Text)
            Else
                MsgBox "输入密码不正确，请重新输入！", vbOKOnly + vbExclamation, "警告"
                txtPassword.SetFocus
                txtPassword.Text = ""
            End If
        End If
    End If

    miCount = miCount + 1
    If miCount = 3 Then
        Me.Hide
    End If
    Exit Sub
End Sub

源代码下载地址http://fswcn.com/一卡通.rar

谁能帮我解决下错误

--------------------编程问答-------------------- 这个是程序代码执行时提示错误
If mrc.EOF = True Then出现“实时错误‘91’对象变量或WITH 块变量未设置”
程序代码

这个代码不在任何过程,函数,属性里 --------------------编程问答-------------------- mrc没有声明或者没有初始化 --------------------编程问答-------------------- Public Function ExecuteSQL(ByVal sql _
  As String, msgstring As String) _
  As ADODB.Recordset
'executes SQL and returns Recordset
  Dim cnn As ADODB.Connection
  Dim rst As ADODB.Recordset
  Dim sTokens() As String

  On Error GoTo ExecuteSQL_Error

  sTokens = Split(sql)
  Set cnn = New ADODB.Connection
  cnn.Open ConnectString
  If InStr("INSERT,DELETE,UPDATE", _
      UCase$(sTokens(0))) Then
      cnn.Execute sql
      msgstring = sTokens(0) & _
        " query successful"
  Else
      Set rst = New ADODB.Recordset
      rst.Open Trim$(sql), cnn, _
        adOpenKeyset, _
        adLockOptimistic
      'rst.MoveLast    'get RecordCount
      Set ExecuteSQL = rst
      msgstring = "查询到" & rst.RecordCount & _
        " 条记录 "
  End If
ExecuteSQL_Exit:
  Set rst = Nothing
  Set cnn = Nothing
  Exit Function
有问题,为什么你用一个private的connection,还在最后加入Set cnn = Nothing,这样相当于连接已经断开,那后面访问记录集肯定不行啊1
--------------------编程问答-------------------- Dim mrc As ADODB.Recordset
声明了啊

Set cnn = Nothing
私有的
那该怎么声明修改呢请教下 --------------------编程问答-------------------- 已经解决了哈是个专家告诉我的
Public Function ExecuteSQL(ByVal sql _
   As String, msgstring As String) _
   As ADODB.Recordset
'executes SQL and returns Recordset
   Dim cnn As ADODB.Connection
   Dim rst As ADODB.Recordset
   Dim sTokens() As String

   On Error GoTo ExecuteSQL_Error

   sTokens = Split(sql)
   Set cnn = New ADODB.Connection
   cnn.Open ConnectString
   If InStr("INSERT,DELETE,UPDATE", _
      UCase$(sTokens(0))) Then
      cnn.Execute sql
      msgstring = sTokens(0) & _
         " query successful"
   Else
      Set rst = New ADODB.Recordset
      rst.Open Trim$(sql), cnn, _
         adOpenKeyset, _
         adLockOptimistic
      'rst.MoveLast     'get RecordCount
      Set ExecuteSQL = rst
      msgstring = "查询到" & rst.RecordCount & _
         " 条记录 "
   End If

'加入此句
   Exit Function

ExecuteSQL_Exit:
   Set rst = Nothing
   Set cnn = Nothing
   Exit Function

ExecuteSQL_Error:
   msgstring = "查询错误: " & _
      Err.Description
   Resume ExecuteSQL_Exit
End Function

补充：VB ,  基础类