问字符串的c#格式错误

EN

public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();
    }

    //Tab 1 Create and close account
    private void Submitbtn_Click(object sender, EventArgs e)
    {
        double x;

        if (OpenRdo.Checked == true && Nametxtbx.TextLength > 0)
        {
            double.TryParse(Nametxtbx.Text, out x);

            // after clicking the button there is
            // no number; it says system.random
            Random acct = new Random();                
            int AccountNumber = acct.Next(5, 1000);
            outputlbl.Text = acct.ToString();
        }

        // list for accounts 
        // This is where it says I have the error
        // that my list is in the wrong format
        var accounts = new List<Account>
        {
            new  Account(Nametxtbx.Text, double.Parse(outputlbl.Text), 0)
        };

        // Write these records to a file
        WriteFile(accounts);

        // message box when you create account
        if (ValidateChildren(ValidationConstraints.Enabled))
        {
            MessageBox.Show("Account Created", "Message", 
                MessageBoxButtons.OK, MessageBoxIcon.Information);
        }
    }

    //writing to the file
    static void WriteFile(List<Account> accts)
    {
        StreamWriter outputFile = File.CreateText("accounts.txt");
        string record;

        foreach (var acct in accts)
        {
            record = $"{acct.Name},{acct.Balance}";
            Console.WriteLine($"Writing record: {record}");
            outputFile.WriteLine(record);
        }

        outputFile.Close();
    }
}