看看下面这个VB登录系统，高手指点下！

Private Sub Cmdlog_Click()
Set cn = New ADODB.Connection
Set rs = New ADODB.Recordset
cn.Open "dsn=CSPE系统"

If Text1.Text = "" Or Text2.Text = "" Then
MsgBox "用户名和密码不能为空！请重新输入", vbOKOnly + vbInformation, "友情提示"
Form2.SetFocus
Exit Sub
End If

Dim sql As String
sql = "select * from 用户 where 用户名='" & Text1.Text & "'and 密码= '" & Text2.Text & "'"
rs.CursorLocation = adUseClient
rs.Open sql, cn, adOpenStatic, adLockReadOnly
With rs
If .State = adStateOpen Then .Close
.Open sql
If rs.EOF Then
Try_times = Try_times + 1
If Try_times >= 3 Then
MsgBox "您已经三次尝试进入本系统，均不成功，系统将自动关闭", vbOKOnly + vbCritical, "警告"
Unload Me
Else
MsgBox "对不起，用户名不存在或密码错误 ！", vbOKOnly + vbQuestion, "警告"
Form1.SetFocus
Text1.Text = ""
Text2.Text = ""
End If
Else
Unload Me
Form2.Show
End If
End With
End Sub
Private Sub Cmdcancel_Click()
Unload Me
End Sub


运行结果显示不能比较text,ntext,image除非使用IS NULL或LIKE运算符

我该怎么办？