Business-Central: JavaScript Addin in the Factbox-Area

Lerxx

I recently wrote a little JavaScript Addin for Business Central, just some things to test around.
I used a PageExtension for that and added my AddIn(Just a simple clickable Picture) to the General Tab of the Customer Card, then I tried to add it to the Factbox area but i just don't seem to get it to work. My Code just isn't executed.

AL:
pageextension 50100 CustExt extends "Customer Card"
{
layout
{

addfirst(General)
{

usercontrol(Demo; demo)
{
trigger ControlReady()
begin
CurrPage.Demo.HelloWorld();
end;
}
}
}
}
This does work but I really don't know how to add the same thing to the Factbox area.

Please help me and thanks in advance.