Using VS C++ functions in Inno Setup

I'm trying to replace some functions made in LazarusLib with functions written in C++ for Inno Setup installer.

So I created a Dynamic-Link Library (DLL) project in Visual studio and added the following code:

InstallerFunctions.h:

extern "C" {    __declspec(dllexport) bool __stdcall CheckPortAvailable(int Port);}

InstallerFunctions.cpp:

#include "pch.h"#include "framework.h"#include "InstallerFunctions.h"#include <windows.h>#include <winsock.h>#include <string>#include <fstream>bool __stdcall CheckPortAvailable(int Port) {    WSADATA WSAData;    SOCKET Sock;    sockaddr_in SockAddr;    int ErrorCode;    if (WSAStartup(MAKEWORD(2, 2), &WSAData) != 0)        return false;    Sock = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);    if (Sock == INVALID_SOCKET)        return false;    ZeroMemory(&SockAddr, sizeof(SockAddr));    SockAddr.sin_family = AF_INET;    SockAddr.sin_addr.s_addr = INADDR_ANY;    SockAddr.sin_port = htons(Port);    ErrorCode = bind(Sock, reinterpret_cast<sockaddr*>(&SockAddr), sizeof(SockAddr));    closesocket(Sock);    WSACleanup();    return (ErrorCode != SOCKET_ERROR);}

This project builds successfully. The project is configured to output the DLL file to \Output\Then I added this to Inno Setup script:

[Files]Source: "..\InstallerFunctions\Output\InstallerFunctions.dll"; DestDir: "{app}"; Flags: ignoreversion

The path is correct. Then I declare the function as following:

function CheckPortAvailable(Port: Integer): Boolean;external 'CheckPortAvailable@files:InstallerFunctions.dll stdcall delayload';

When I try to call CheckPortAvailable I get the following error:Could not call proc.

I tried to use DLL explorer to find the functions I require and DLL explorers are able to find the functions. Any idea what else can I try?

Edit:It appears that the function is recognized, so the issue defenitly lies in C++ project: