It is often best to post information asked for after
the post asking for it. I am not going to reread the first post everytime so please, in future, add new information in a new post.
I asked, in my previous post, for you to post your sources.list up for us to see. I am not just going to take you on your word, even though I am asure it is fine, so please post your complete sources.list file here for us to see.
Occassionaly if I have trouble with apt-get I use aptitude instead. Try this command
and they try
Understand that you are trying to upgrade to a beta version of the next stable, there will be changes and some are very visible. There may be packages that are currently not able to be upgraded as you are trying to upgrade your entire OS from one version to another. I would actually recommend that you save your download bandwidth and instead download a current Debian Testing cd or dvd (dvd maybe better) and install Wheezy as a fresh clean install.