I have included the stack trace for more info.

11/2/2006 9:35:32 AM
Source: mscorlib
Message: Value cannot be null.
Parameter name: type
Stack:    at System.Activator.CreateInstance(Type type, BindingFlags bindingAttr, Binder binder, Object[] args, CultureInfo culture, Object[] activationAttributes)
   at System.Activator.CreateInstance(Type type, Object[] args)
   at MicroFour.StrataFrame.UI.Windows.Forms.ChildFormDialog.CreateForm(Object[] Arguments)
   at MicroFour.StrataFrame.UI.Windows.Forms.ChildFormDialog.ShowDialog(Object[] Arguments)
   at MicroFour.StrataFrame.UI.Windows.Forms.ChildFormDialog.ShowDialog()
   at BBS.GUI.frmClientInfo.MaintBankRel_AfterButtonClick() in C:\FactorSoftV3\GUI\ClientInfo\frmClientInfo.vb:line 205
   at BBS.GUI.BaseControls.MaintStrip.button_Click(Object sender, EventArgs e)
   at System.Windows.Forms.Control.OnClick(EventArgs e)
   at DevExpress.XtraEditors.BaseButton.OnClick(EventArgs e)
   at DevExpress.XtraEditors.BaseButton.OnMouseUp(MouseEventArgs e)
   at System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks)
   at System.Windows.Forms.Control.WndProc(Message& m)
   at DevExpress.Utils.Controls.ControlBase.WndProc(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
   at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)

public class Form1 : System.Windows.Forms.Form
{
    public Form1(string param1, string param2, string param3) { }
}

Then you're call to childFormDialog.ShowDialog() will look like this:

childFormDialog.ShowDialog("param1", "param2", "param3");

The signature of the method is like this:

public DialogResult ShowDialog(params object[] parameters) {}

The keyword being the "params" at the beginning.  It means that you can add as many parameters as you want and separate them with commas and the compiler will pass them all as one big object array.  It's smart like that