Yes that's the LTS version IIRC. I wasn't planning on upgrading until then next LTS version due to be released in the new year.
I think you should upgrade to the newer version, then try again. Maybe that PPA doesn't support older version Ubuntu.
It was the Bitcointalk forum that inspired us to create Bitcointalksearch.org - Bitcointalk is an excellent site that should be the default page for anybody dealing in cryptocurrency, since it is a virtual gold-mine of data. However, our experience and user feedback led us create our site; Bitcointalk's search is slow, and difficult to get the results you need, because you need to log in first to find anything useful - furthermore, there are rate limiters for their search functionality.
The aim of our project is to create a faster website that yields more results and faster without having to create an account and eliminate the need to log in - your personal data, therefore, will never be in jeopardy since we are not asking for any of your data and you don't need to provide them to use our site with all of its capabilities.
We created this website with the sole purpose of users being able to search quickly and efficiently in the field of cryptocurrency so they will have access to the latest and most accurate information and thereby assisting the crypto-community at large.
sudo apt-add-repository ppa:k-dg/protoshares
sudo apt-get update
W: Failed to fetch http://ppa.launchpad.net/k-dg/protoshares/ubuntu/dists/precise/main/source/Sources 404 Not Found
W: Failed to fetch http://ppa.launchpad.net/k-dg/protoshares/ubuntu/dists/precise/main/binary-amd64/Packages 404 Not Found
W: Failed to fetch http://ppa.launchpad.net/k-dg/protoshares/ubuntu/dists/precise/main/binary-i386/Packages 404 Not Found
E: Some index files failed to download. They have been ignored, or old ones used instead.
sudo apt-get update && sudo apt-get install -y yasm git make g++ build-essential libminiupnpc-dev libboost-all-dev libdb++-dev libgmp-dev libssl-dev dos2unix
cd && rm -rf ./ProtoShares
git clone https://github.com/InvictusInnovations/ProtoShares.git
cd ./ProtoShares/src && make -f makefile.unix -j`grep -c ^processor /proc/cpuinfo`
W: Failed to fetch http://ppa.launchpad.net/k-dg/protoshares/ubuntu/dists/precise/main/source/Sources 404 Not Found
W: Failed to fetch http://ppa.launchpad.net/k-dg/protoshares/ubuntu/dists/precise/main/binary-amd64/Packages 404 Not Found
W: Failed to fetch http://ppa.launchpad.net/k-dg/protoshares/ubuntu/dists/precise/main/binary-i386/Packages 404 Not Found
E: Some index files failed to download. They have been ignored, or old ones used instead.
sudo apt-add-repository ppa:k-dg/protoshares
sudo apt-get update
sudo apt-get install protoshares-qt
sudo apt-get update && sudo apt-get install -y yasm git make g++ build-essential libminiupnpc-dev libboost-all-dev libdb++-dev libgmp-dev libssl-dev dos2unix
cd && rm -rf ./ProtoShares
git clone https://github.com/InvictusInnovations/ProtoShares.git
cd ./ProtoShares/src && make -f makefile.unix -j`grep -c ^processor /proc/cpuinfo`
W: Failed to fetch http://ppa.launchpad.net/k-dg/protoshares/ubuntu/dists/precise/main/source/Sources 404 Not Found
W: Failed to fetch http://ppa.launchpad.net/k-dg/protoshares/ubuntu/dists/precise/main/binary-amd64/Packages 404 Not Found
W: Failed to fetch http://ppa.launchpad.net/k-dg/protoshares/ubuntu/dists/precise/main/binary-i386/Packages 404 Not Found
E: Some index files failed to download. They have been ignored, or old ones used instead.
sudo apt-add-repository ppa:k-dg/protoshares
sudo apt-get update
sudo apt-get install protoshares-qt
sudo apt-get update && sudo apt-get install -y yasm git make g++ build-essential libminiupnpc-dev libboost-all-dev libdb++-dev libgmp-dev libssl-dev dos2unix
cd && rm -rf ./ProtoShares
git clone https://github.com/InvictusInnovations/ProtoShares.git
cd ./ProtoShares/src && make -f makefile.unix -j`grep -c ^processor /proc/cpuinfo`
sudo apt-get update && sudo apt-get install -y yasm git make g++ build-essential libminiupnpc-dev libboost-all-dev libdb++-dev libgmp-dev libssl-dev dos2unix
cd && rm -rf ./ProtoShares
git clone https://github.com/InvictusInnovations/ProtoShares.git
cd ./ProtoShares/src && make -f makefile.unix -j`grep -c ^processor /proc/cpuinfo`