Declaring C dll functions in visual basic

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I am learning to make dll for Visual Basic, so I made this:

DLL in C:

// FirstDLL.cpp : Defines the exported functions for the DLL application.
//

#include "stdafx.h"
#include "stdio.h"

extern "C"
{
__declspec(dllexport) int sestej(int a, int b)
{
    int c;
    c = a + b;
    return c;
}
}

Visual Basic:

Public Class Form1

    Declare Function  sestej Lib "C:\Users\Blaž\Documents\Visual Studio     2013\Projects\FirstDLL\Debug\FirstDLL.dll" (ByVal x As Integer, ByVal y As Integer)

Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click

    Dim vnos1, vnos2, izhod As Integer

    vnos1 = Convert.ToDecimal(VnosX.Text)
    vnos2 = Convert.ToDecimal(VnosY.Text)

    sestej(vnos1, vnos2)

    lblvsota.Text = izhod

End Sub

End Class

When I run it i get this error: An unhandled exception of type 'System.Runtime.InteropServices.MarshalDirectiveException' occurred in WindowsApplication2.exe

Additional information: PInvoke restriction: cannot return variants.

I obviously did something wrong but I can't find it anywhere.

Pls help :)

asked 35 secs ago

user3457132

1