Conversion XmlNode.InnerText to Double

the condition Double.TryParse(node.ChildNodes[4].InnerText, out course) doesn't work.

 foreach (XmlNode node in XmlDoc.SelectNodes("/ValCurs/Valute"))  
                {
                    if (node.ChildNodes[1].InnerText == curr_name) // CharCode
                    {
                       // throw new Exception(node.ChildNodes[4].InnerText);  //returns 2.085 but next condition doesn't work
                        if (Double.TryParse(node.ChildNodes[4].InnerText, out course)) // course value, nominal = 100
                        {     
                            if (Int32.Parse(node.ChildNodes[2].InnerText) == 10) course *= 10;   //for RUB, BYR nominal = 10
                            if (Int32.Parse(node.ChildNodes[2].InnerText) == 1000) course /= 10; //for JPY, HUF nominal = 1000
                            return course;
                        }
                    }