Patcher

I want to change the programme when he run. To do it I use SDK fonction but i can read the progamme that run but I can write on it can you tell me why. this is some of the code char tab[100]; unsigned long longu; MODULEENTRY32 me32; HANDLE hProcess; HWND target; DWORD proc_id; // get Handel to window I''m looking for => WORK target = FindWindow(NULL, target_window); // get id of this windows => WORK GetWindowThreadProcessId(target, &proc_id); //get base offset => WORK GetProcessModule(proc_id, &me32, sizeof(MODULEENTRY32)); // ask to have all access to process => look to WORK hProcess = OpenProcess (PROCESS_ALL_ACCESS, FALSE, proc_id); // read some data from process => WORK ReadProcessMemory(hProcess,(LPVOID)base_offset,tab,100,&longu); // write somme data from process => DON''T WORK WriteProcessMemory(hProcess, (LPVOID)(base_offset + patch_offset[c]), &patch[c], 1, NULL); //return 998 Invalid access to memory location. DWORD error = GetLastError(); // close handle CloseHandle (hProcess); So if you know why it don''t work or how I can do it tell me