Hooking pr_write problem

[cd0c]

Trying to hook pr_write in ff. I'm injecting dll to a process, process is not crashing but hooked proc in not calling. Help plz to find error in code.

typedef int (*PR_Write)(void* fd, const void* buf, int amount);
PR_Write old = (PR_Write)(ProcAddress);

int HookedPR_Write(void* fd, char* buf, int amount) {

MessageBoxA(NULL,"hooked func","",MB\_OK);   
return old(fd, buf, amount);

}

BYTE* Trampoline(BYTE* src, BYTE* dst, int len) {
BYTE patch[5];
BYTE* addr = (BYTE*)VirtualAlloc(NULL, len, MEM_RESERVE | MEM_COMMIT, PAGE_EXECUTE_READWRITE);
SIZE_T written;
memcpy_s(addr, len, src, len);
uintptr_t gatewayrelative = src - addr - 5;

memcpy\_s(patch, 1, "\\xE9", 1);

\*(uintptr\_t\*)(patch + 1) = gatewayrelative;

if (!WriteProcessMemory(GetCurrentProcess(), addr + len, patch, 5, &written))
    MessageBoxA(NULL, "WriteProcessMemory error", "", MB\_OK);
Detour(src, dst, len);
return addr;

}

void Detour(BYTE* src, BYTE* dst, int len) {
BYTE patch[11];
SIZE_T written;

uintptr\_t relative\_addr = dst - src - 5;
memcpy\_s(patch, 1, "\\xE9", 1);
\*(uintptr\_t\*)(patch + 1) = relative\_addr;
memset(patch + 5, 0x90, len - 5);
if (!WriteProcessMemory(GetCurrentProcess(), ProcAddress, patch, sizeof(patch), &written))
    MessageBoxA(NULL, "WriteProcessMemory detour error", "Caption", MB\_OK); 

}

BOOL APIENTRY DllMain(HMODULE hModule, DWORD ul_reason_for_call, LPVOID lpReserved)
{
ProcAddress = (void*)GetProcAddress(LoadLibraryA("nss3.dll"), "PR_Write");
int stopSize = 0;
while (*((BYTE*)ProcAddress + stopSize) != 0xFF) {
stopSize++;
}
if (ul_reason_for_call == DLL_PROCESS_ATTACH)
{
if (ProcAddress != NULL) {
old = (PR_Write)Trampoline((BYTE*)ProcAddress, (BYTE*)HookedPR_Write, stopSize);
}
}
return TRUE;
}