VB后台按键我的代码有什么毛病为什么游戏无动于衷

Private Declare Function PostMessage Lib "user32" Alias "PostMessageA" (ByVal hwnd As Long, ByVal wMsg As Long, ByVal wParam As Long, lParam As Any) As Long
Private Declare Function FindWindow Lib "user32" Alias "FindWindowA" (ByVal lpClassName As String, ByVal lpWindowName As String) As Long
Private Declare Function GetWindowThreadProcessId Lib "user32" (ByVal hwnd As Long, lpdwProcessId As Long) As Long

Private Sub Form_Load()

End Sub

Private Sub Timer1_Timer()
Dim hwnd As Long ' 储存 FindWindow 函数返回的句柄
hwnd = FindWindow(vbNullString, "YB_OnlineClient") ' 取得进程标识符
If hwnd = 0 Then
Label1.Caption = "未运行"

Else
Label1.Caption = "已运行"
Text1.Text = hwnd
PostMessage hwnd, WM_KEYDOWN, VK_F1, 0& '按下F1键
PostMessage hwnd, WM_UP, VK_F1, 0& '释放F1键
End If
End Sub
问题补充：VB，后台按键还是不行啊，，

谁知道VB按键的代码？ VB后台运行代码 VB里用按键控制事件的语句谁能帮我举个例子啊？代码 vb的代码有什么用 求VB后台打开网页代码 帮我看下这段vb代码有什么问题，谢谢 哪有VB的代码！ 哪个朋友有.do的java后台代码发一份让我看看？ VB的按键问题 我的vb计算器代码