where is virtualbox there is none in the repos lol , so how the hell can you install virtualbox from aptus that wil not work.. :-[
very strange behaver if you ask me ( there is not one file in synaptic from virtualbox ) that is like a mercedescar without any wheels)
it is in the Debian's repos so refresh package list and try again.
I DO NOT tolerate bad behavior, so please do not shake and do not use BLOCK letters all the time, it is not a kinder garden.
It is the last warning.