高手帮我看看这个VB程序出了什么问题？？

Public n As Integer
Dim txtSQL As String

Private Sub Form_Load()
n = 0 'n保存登录的次数
End Sub
Private Sub cmdOK_Click()
Dim mrc As ADODB.Recordset
txtSQL = "select * from oper where 用户名='" & Trim$(txtName.Text) & "' And 密码 = '" & Trim$(txtKey.Text) + "'"
Set mrc = exesql(txtSQL)
If mrc.RecordCount = 0 Then '未找到用户记录
n = n + 1
If n < 10 Then
MsgBox "没有这个用户，继续登录", vbOKOnly + vbExclamation, "信息提示"
txtName.Text = ""
txtKey.Text = ""
txtName.SetFocus
Else
MsgBox "已登录失败十次，退出系统", vbOKOnly + vbExclamation, "信息提示"
mrc.Close
Unload Me
End If
Else
userlevel = Trim(mrc.Fields("级别"))
mrc.Close
Unload Me
Menu.Show '调用窗体
End If