I am trying to write a code in C# using event between to WinForms. I would like to change color text in a RichTextBox of the 1. form and the 2. form using RadioButton (RadioButtons are on the 2. form), but when i declare the variable: `Color valgtFarge = null;` I get this error message: `Cannot convert null to 'System.Drawing.Color' because it is a non-nullable value type`. What am I doing wrong?
The function:

```
private void rtf2_TextChanged(object sender, EventArgs e)
{
    Color colorChoice = null;

    if (rbtnBlack.Checked)
        colorChoice = Color.Black;

    //same here for the others RadioButtons

    if (myEventHandler != null && rtf2.Text.Length != 0)
    {
        myEventHandler(this, new Form1EventArgs(rtf2.Text.Substring(rtf2.Text.Length - 1),
            colorChoice));
    }
}

```