Deriving a class from TGroupBox

[h***@gmail.com]

Hi All!
The problem: Why can't I derive a class from TGroupbox or
TCustomGroupBox and make a package of it? It seems that every thing is
OK: Code compiles and the component sits on the palette but when I want
to put the component in a form it disappears from the palette. What's
the matter?
Thank you all

[h***@gmail.com]

just bringing topic to top