C＃向图表添加负值

Question

Can anybody help me, why I can't add negative values to the chart (windows form)? the part of code is below:

chart1.Series["Series1"].Points.AddXY(a, Convert.ToDouble(rx_str_copy));

for example as input: rx_str_copy = "-128.00"

It throws a communicate that input string is wrong. With positive values I don't have any problems

What is wrong?

I'm updating my question:

So far I've tried to add values without dot, so it was just like integer covered in string and then converted to double. Now I'm trying to add values with dot so now it's double covered in string and then convert to double.

I realized problem with negative and positive values also. So the problem lies with dot in string. Can anybody help with that?

Answer 1

A simple test case like this works perfectly for me. For your case, is a a double already?

public Form1 ()
{
    InitializeComponent();
}

private void chart1_Click ( object sender, EventArgs e )
{
    string rx_str_copy = "-128.00";
    chart1.Series["Series1"].Points.AddXY(-1.00, Convert.ToDouble(rx_str_copy));
}