Hi Peter,
by calling Button in Form1 when clicking a button on Form2 I understand that you want to invoke the event click on the button in the form1 right?
If that is the case you must first go to the source code of the Form 1 and make the method button1_click(...) public
e.g.:
public void button1_Click(object sender, EventArgs e)
{
}
Then in the form2 button click event you can call the method in the form1
public void button1_Click(object sender, EventArgs e)
{
Form1 frm = new Form1();
frm.button1_Click(sender, e);
}
Hope that helps.