为什么模拟按键失败？该如何解决

为什么模拟按键失败？
SendMessage hwd, WM_SETTEXT, 0, ByVal Text3.Text
SetForegroundWindow hwd
keybd_event 13, MapVirtualKey(13, 0), 0, 0 '??
Sleep 500
keybd_event 13, MapVirtualKey(13, 0), KEYEVENTF_KEYUP, 0


以上代码出果单独放在command命令里面，点击按钮是可以完成写入加发送的。但是放在速个程序里面，却只能写入不能模拟按键，这是为什么呢？有什么解决的方法吗，试了几种按键方法，都是分离开后可行，加到自动代码里面就不行了，有谁知道告诉我一下吧!谢谢了...

[解决办法]
不用获得什么焦点，直接给该控件发送文本和回车消息

VB code

Option ExplicitPrivate Const WM_SETTEXT = &HCPrivate Const WM_KEYDOWN = &H100Private Declare Function SendMessage Lib "user32" Alias "SendMessageA" (ByVal hwnd As Long, _                                                                        ByVal wMsg As Long, _                                                                        ByVal wParam As Long, _                                                                        lParam As Any) As LongPrivate Sub Command1_Click()    SendMessage Text1.hwnd, WM_SETTEXT, 0, ByVal Text3.Text    SendMessage Text1.hwnd, WM_KEYDOWN, &HD, 0&End Sub