Problema de creación de ZwCreateThread

HANDLE hProcess = OpenProcess(PROCESS_ALL_ACCESS,0,dwpid);//dwpid es un ID de proceso del sistema

USER_STACK stack = {0};

DWORD ret;

ULONG n = 1024*1024;//1MB

ret=ZwAllocateVirtualMemory(hProcess, &stack.

ret= ZwAllocateVirtualMemory(hProcess, &p, 0, &n, MEM_COMMIT, PAGE_READWRITE);

ULONG x; n = PAGE_SIZE;

ret= ZwProtectVirtualMemory(hProcess, &p, &n, PAGE_READWRITE | PAGE_GUARD,

CONTEXTO contexto = {CONTEXT_FULL};

ret= ZwGetContextThread(GetCurrentThread(),&context);

context.PAGE_READWRITE | PAGE_GUARD, &x)Esp = ULONG(stack.ExpandableStackBase) - 2048;

context.Esp = ULONG(stack.ExpandableStackBase) - 2048;