Why does CTRL+X, CTRL+V etc. not work?

When i open a child form, like this:

frmEl.MdiParent = Me
frmEl.Show()

Then i can't use the standard shortcutkeys like CTRL+V etc. in a RTF box. If i open the form without the  frmEl.MdiParent = Me, then all works perfect.

Anybody knows what are going wrong

I have made other aplications, where everything works ok, but not with this one. I have tryed to make a empty form, only with a RTF boks on, it's the same result.

I am using Visual Studio 2005

Please help