Hi, I've been trying to install ROS in Ubuntu 13.04. But the moment I type in sudo apt-get install ros-hydro-desktop-full It says "Unable to correct problems, you have held broken packages." I am not sure how to fix it. I've been trying to install this for about two weeks and actually tried every solution I found on the internet. But nothing is working. Please help me out. Not sure how to get rid of this problem.