Error calling the form screen

I'm having trouble loading a menu through another screen and following my code below. What would be a possible solution for such an error?

public partial class frmMenu : Form
{
    public frmMenu()
    {
        InitializeComponent();
    }
    private void guichesToolStripMenuItem_Click(object sender, EventArgs e)
    {
        frmCadastroGuiche frm = new frmCadastroGuiche();
        frm.ShowDialog();
    }
}

Screen that should be loaded when you click the button on the guiche.

public partial class frmCadastroGuiche : Form
{
    public frmCadastroGuiche()
    {
        carregarCombos();
        carregando = true;
        carregargrid();
        carregando = false;
        InitializeComponent();
    }
    bool pularFiltro = false;
    bool carregando = false;
    public bool setDatabase(Sele.Classes.clsDatabase oDB)
    {
        try
        {
            oAtende.oDB = oDB;
            carregarCombos();
            carregando = true;
            carregargrid();
            carregando = false;
            return true;
        }
        catch (Exception)
        {
            return false;
        }
    }
    DataTable dtGuiche = new DataTable();
    public void carregarCombos()
    {
        lstTipoSenha_id.DataSource = oAtende.dtTipoSenha;
        oAtende.dtTipoSenha = oAtende.getSenhaTipo();
        lstTipoSenha_id.DisplayMember = "Tipo da Senha";
        lstTipoSenha_id.ValueMember = "id";
        lstTipoSenha_id.DataSource = oAtende.dtTipoSenha;
    }    
    private void carregargrid()
    {
        carregando = true;
        dg.CurrentCell = null;
        dg.AutoGenerateColumns = false;

        dtGuiche = oAtende.getGuiches("");
        dg.DataSource = dtGuiche.DefaultView;

        dg.CurrentCell = null;

        dg.ClearSelection();
        carregando = false;
    }
}

Below this would have the codes of the save and delete buttons in the fields that were passed, but I did not put it because I did not find it necessary I believe the error is not there.