Event keeps null value

//Child form
public partial class InventuraForm
{
    public delegate void NekiDelegat();
    public event NekiDelegat MojEvent;  


    public void SendEvent()
    {
        if (MojEvent != null) MojEvent();
    }

    public void tsbSpremiZatvori_Click(object sender, EventArgs e)
    {
       //some code

        SendEvent();
    }
}           


//Parent form
public partial class InventuraFormPregled 
{ 
    InventuraForm _inv = null;

  public InventuraFormPregled()
    {
        InitializeComponent();

        _inv = new InventuraForm();
        _inv.MojEvent += new InventuraForm.NekiDelegat(LoadGridData);          

    }     

 private void LoadGridData()
 {
 //some code
 }

}