如果在VB中使用WriteProcessMemory函數寫入不成功，可能有以下幾種原因和解決方法：

1. 權限問題：確保當前用戶具有足夠的權限來寫入目標進程的內存。如果需要管理員權限，可以嘗試以管理員身份運行VB程序。

2. 目標進程句柄問題：確保使用正確的目標進程句柄。可以通過OpenProcess函數獲取到目標進程的句柄。

3. 內存保護問題：目標進程的內存可能被保護，無法直接寫入。可以使用VirtualProtectEx函數修改內存的保護屬性，然后再進行寫入操作。

4. 寫入數據長度錯誤：確保寫入的數據長度正確。如果寫入長度超過了目標內存區域的大小，可能會導致寫入失敗。

以下是一個使用WriteProcessMemory函數寫入數據的示例代碼：

Imports System.Runtime.InteropServices

Public Class Form1

    '定義常量和API函數
    Private Const PROCESS_ALL_ACCESS As Integer = &H1F0FFF
    Private Const WM_CLOSE As Integer = &H10

    <DllImport("kernel32.dll")>
    Private Shared Function OpenProcess(ByVal dwDesiredAccess As Integer, ByVal bInheritHandle As Boolean, ByVal dwProcessId As Integer) As IntPtr
    End Function

    <DllImport("kernel32.dll", SetLastError:=True)>
    Private Shared Function WriteProcessMemory(ByVal hProcess As IntPtr, ByVal lpBaseAddress As IntPtr, ByVal lpBuffer As Byte(), ByVal nSize As Integer, ByRef lpNumberOfBytesWritten As Integer) As Boolean
    End Function

    <DllImport("kernel32.dll")>
    Private Shared Function CloseHandle(ByVal hObject As IntPtr) As Boolean
    End Function

    '寫入數據的函數
    Private Sub WriteData(ByVal processId As Integer, ByVal address As IntPtr, ByVal data As Byte())
        '打開目標進程
        Dim processHandle As IntPtr = OpenProcess(PROCESS_ALL_ACCESS, False, processId)
        If processHandle = IntPtr.Zero Then
            MessageBox.Show("無法打開目標進程")
            Return
        End If

        '寫入數據
        Dim bytesWritten As Integer = 0
        Dim success As Boolean = WriteProcessMemory(processHandle, address, data, data.Length, bytesWritten)
        If Not success Then
            MessageBox.Show("寫入數據失敗")
        End If

        '關閉進程句柄
        CloseHandle(processHandle)
    End Sub

    '按鈕點擊事件
    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        '示例：寫入一個整數值到目標進程的指定地址
        Dim processId As Integer = 1234 '目標進程ID
        Dim address As IntPtr = New IntPtr(&H12345678) '目標進程中的地址
        Dim value As Integer = 100 '要寫入的值

        Dim data As Byte() = BitConverter.GetBytes(value)
        WriteData(processId, address, data)
    End Sub
End Class

希望對你有幫助！