Private Sub Form_Load()
    Command1.TabStop = False
End Sub

Private Sub Text1_KeyDown(KeyCode As Integer, Shift As Integer)
    If KeyCode = vbKeyTab And Len(Text1.Text) = 6 Then
        Command1.Value = True
    End If
End Sub

Private Sub Command1_Click()
    MsgBox "因為 Tab 會將 focus 移到物件上" & _
            vbCrLf & "而無法觸發事件；在適當時候加入" & _
            vbCrLf & "物件.TabStop = False 即可解決!"
End Sub

Private Sub Form_Load()
    Text1.TabIndex = 0
    Command1.TabIndex = 1
End Sub
Private Sub Text1_Change()
If Len(Text1.Text) = 6 Then
        Command1.Value = True
  End If
End Sub
Private Sub Command1_GotFocus()
    If Len(Text1.Text) <> 6 Then Exit Sub
    Command1.Value = True
End Sub
Private Sub Command1_Click()
    MsgBox "Form 上有多個物件的另一種解法，供大家參考"
End Sub