Problem with string array?

Question

I have a problem with this code, because it gives me following error message 

Object reference not set to an instance of an object when I use the line

values[countValues] = reader2.GetString("textinfo"); in the code below

Can someone help me?

public static string[] values;
int countValues = 0;

using (var connection = new MySqlConnection(connString))
{
    connection.Open();
    string query = "select * from showvalues where idvalue = '" + idStatus + "'";
    using (var command2 = new MySqlCommand(query, connection))
    {
        using (var reader2 = command2.ExecuteReader())
        {
            while (reader2.Read())
            {
          
               listBoxMeasurement.Items.Add(reader2.GetString("textinfo"));
               values[countValues] = reader2.GetString("textinfo");
               countValues++;
            }
           countValues = 0;
           connection.Close();
         } 
    }
}