Visible property in C#

public delegate void AddDataDelegate(String myString);
public AddDataDelegate myDelegate;

void scanOnOff()
{
serialPort1.DataReceived += new SerialDataReceivedEventHandler(serialPort1_DataReceived);
myDelegate = AddDataMethod;
}

void serialPort1_DataReceived(object sender, SerialDataReceivedEventArgs e)
{
SerialPort port = (SerialPort)sender;
string indata = port.ReadLine();
Console.WriteLine(indata);
richTextBox1.Invoke(myDelegate, new Object[] { indata });
}

public void AddDataMethod(String myString)
{
if (myString.Contains("0x0000"))
{
newtemperature.Visible = false;
neue_temperatur.Visible = false;
}
}