Ubuntu – How to run ‘apt-get install’ to install all dependencies?

I am running this in ubuntu server installation:

sudo apt-get install git-core gnupg flex bison gperf build-essential \
  zip curl libc6-dev libncurses5-dev:i386 x11proto-core-dev \
  libx11-dev:i386 libreadline6-dev:i386 libgl1-mesa-glx:i386 \
  libgl1-mesa-dev g++-multilib mingw32 openjdk-6-jdk tofrodos \
  python-markdown libxml2-utils xsltproc zlib1g-dev:i386

but I am getting this:

Reading package lists...
Building dependency tree...
Reading state information...
curl is already the newest version.
gnupg is already the newest version.
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
 build-essential : Depends: gcc (>= 4:4.4.3) but it is not going to be installed
                   Depends: g++ (>= 4:4.4.3) but it is not going to be installed
 g++-multilib : Depends: cpp (>= 4:4.7.2-1ubuntu2) but it is not going to be installed
                Depends: gcc-multilib (>= 4:4.7.2-1ubuntu2) but it is not going to be installed
                Depends: g++ (>= 4:4.7.2-1ubuntu2) but it is not going to be installed
                Depends: g++-4.7-multilib (>= 4.7.2-1~) but it is not going to be installed

How can I fix this?