I can't install xojo. When I click install in the software center it's not progressing. In the terminal it's stuck in : gichan02@gichan02-Latitude-D520:~$ sudo apt-get install xojo [sudo] password for gichan02: Reading package lists... Done Building dependency tree Reading state information... Done The following extra packages will be installed: xojo-bin The following NEW packages will be installed: xojo xojo-bin 0 upgraded, 2 newly installed, 0 to remove and 0 not upgraded. Need to get 209 MB/209 MB of archives. After this operation, 596 MB of additional disk space will be used. Do you want to continue? [Y/n] Y 0% [Working] then after waiting for an hour for progress it says: Failed to fetch https://private-ppa.launchpad.net/commercial-ppa-uploaders/xojo/ubuntu/pool/main/x/xojo/xojo-bin_2013.41-0ubuntu1_i386.deb Could not resolve host: private-ppa.launchpad.net So I added apt repository for 'private-ppa': deb https://ging-giana:[email protected]/commercial-ppa-uploaders/xojo/ubuntu trusty main Then when I try 'apt-get update': GPG error: https://private-ppa.launchpad.net trusty Release: The following signatures were invalid: NODATA 2 Then I noticed something the Software Sources:Other software TAB: Added by software-center; credentials stored in /etc/apt/auth.conf https://private-ppa.launchpad.net/commercial-ppa-uploaders/xojo/ubuntu So i go to the '/etc/apt/auth.conf' ,but It cannot be opened and it is not a keyserver. So i uncheck: Added by software-center; credentials stored in /etc/apt/auth.conf https://private-ppa.launchpad.net/commercial-ppa-uploaders/xojo/ubuntu GPG error was gone. But then again I found myself at the beginning of the problem.STUCK at '0% [Working]'. 'Xojo' is the only application that I can't install.Any explanation why is it like that?