I have a ChildFormDialog control on a form, and have set up the ChildForm and BO Translations for it.  The child form is coming from a dll and is an inherited form.  In my code I call ChildFormBank.ShowDialog() and get the attached error message every time.

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)

 

OK, I sort of figured it out.  Not sure what this means and pretty sure it's not supposed to work this way.  I have a local form which I set as the ChildForm, and this works fine...no problems.  This works without creating an instance of the local form.  When I try to set the ChildForm to a form coming from a referenced DLL it gives me the error.  However, if I create an instance of the form (with any name) it works fine.  So basically if it's a form from the same project no instance is needed, but if it's coming from a referenced dll then you must create an instance first.

This code works for forms in same project:

ChildFormDialog1.ShowDialog()

This code works for forms from dlls where ChildFormDialog1 has ChildForm=frmChildForm:

Dim ChildFormDLL as New frmChildForm
ChildFormDialog1.ShowDialog

Actually, you can use a referenced form from a DLL.  But the problem may be that the full name (i.e. YourNameSpace.YourForm) may not be valid through the reference that is being specified.  You may need to load the assembly.  For example, open your designer file and go to the ChildForm property in the designer file.  You will see the name of the form like something I mentioned above.  See if your activator.CreateInstance works with the full name rather than the type:

Activator.CreateInstance("YourNameSpace.YourFormName")