C# SqlDataReader Error: System.IndexOutOfRangeException: AdminId

I trying to Implement Role based security, Page access and Show/Hide Menu items based on Role in ASP.Net

in this code when entered correct username and password then all code run perfectly but when entered wrong username and password then generating error "System.IndexOutOfRangeException: AdminId"

Code File:

protected void AdminLogOn_Click(object sender, EventArgs e)
{
    if (inputName.Text == "" && inputName.Text == string.Empty)
    {
        lblMessage.Text = "Please Enter User Name!";

    }
    else if (inputPassword.Text == "" && inputPassword.Text == string.Empty)
    {
        lblMessage.Text = "Please Enter Password!";
    }
    else
    {
        int userId = 0;
        string roles = string.Empty;
        objBussinessObj.UserName = inputName.Text;
        objBussinessObj.Password = inputPassword.Text;

        SqlDataReader reader = objBussinessLogic.ValidateAdminLogin(objBussinessObj);
        reader.Read();

        userId = Convert.ToInt32(reader["AdminId"]);
        roles = reader["Roles"].ToString();


        switch (userId)
        {
            case -1:
                lblMessage.Text = "Username and/or password is incorrect.";
                break;
            default:
                FormsAuthenticationTicket ticket = new FormsAuthenticationTicket(1, inputName.Text, DateTime.Now, DateTime.Now.AddMinutes(2880), RememberMe.Checked = false, roles, FormsAuthentication.FormsCookiePath);
                string hash = FormsAuthentication.Encrypt(ticket);
                HttpCookie cookie = new HttpCookie(FormsAuthentication.FormsCookieName, hash);

                if (ticket.IsPersistent)
                {
                    cookie.Expires = ticket.Expiration;
                }
                Response.Cookies.Add(cookie);
                Response.Redirect(FormsAuthentication.GetRedirectUrl(inputName.Text, RememberMe.Checked = false));


                break;
        }
    }
}
//class file code:
public SqlDataReader ValidateAdminLogin(BussinessObj objBussiness)
{
    SqlParameter[] param = new SqlParameter[3];
    param[0] = new SqlParameter("@Mode", "ChkAdminLogin");
    param[1] = new SqlParameter("@UserName", objBussiness.UserName);
    param[2] = new SqlParameter("@Password", objBussiness.Password);

    return objDataAccess.ExecuteReader(_spName, param);
}

stored procedure:

IF (@Mode='ChkAdminLogin') 
BEGIN
	SELECT @AdminId = AdminId, @RoleId = RoleId
      FROM Admins WHERE Username = @UserName AND [Password] = @Password
      
      IF @AdminId IS NOT NULL
      BEGIN
                              
                  SELECT @AdminId [AdminId],
                              (SELECT RoleName FROM Roles
                               WHERE RoleId = @RoleId) [Roles] -- User Valid
            
      END
      ELSE
      BEGIN
            SELECT -1 -- User invalid.
      END
END