linkgrabber doesn't work properly

I have jdownloader installed on 2 computers.
1 a mac with osx 10.5.8 and another one with 10.6.2 installed.
Linkgrabber automatically copies the urls to linkgrabber on the one with 10.5.8 and not to the other one.
Is this a preference issue or a snow leopard issue?

[Jiaz]

you have to enable clipboard monitoring
its a button in the menubar wit the buttons, it has a checkbox in it, enable it

Thanks.