PrintPreview/ Print datagrid in MDI

[John2009]

Hi Guys,
I have some MDI C# project.
The "main" window opens childs:

SomeType1 childForm = new SomeType1;
childForm.MdiParent = this;
childForm.Show();

...

SomeType2 childForm = new SomeType2;
childForm.MdiParent = this;
childForm.Show();

...

Each "childForm" has its own DataGrid placed on it.
I need to implement print preview / print functionality.

I've placed some stuff like this:

private void printPreviewToolStripMenuItem_Click(object sender, EventArgs e)
{
Form activeChild = this.ActiveMdiChild;
printPreviewDialog1.ShowDialog(activeChild);
}

But preview dialog is empty...

How to do it?
Thanks in advance.