How to "put some 'source' URIs in your sources.list"?

**machine**: Toshiba MK1646GSX, intel atom CPU@1.60Ghz, 2048Mb. 32bit. **OS**: LINUX LITE 3.8 i was trying to install the PIDGIN dependencies: ~> sudo apt-get build-dep pidgin and then i got this instead of installing the build-dep: Reading package lists... Done E: You must put some 'source' URIs in your sources.list so i searched and i found sources say that i should rm -rf the sources.list, and then apt-get update and the list will create itself. the results were not good and like what i expected, the list didn't create itself. after that i made a new list with the same content, i tried to make sure about every line and does it own deb-src. all lines are correct. but the Error still exits when i try to install the build-dep. what to do? --- sources.list copied from the justpaste link: ###### Ubuntu Main Repos deb http://archive.ubuntu.com/ubuntu xenial main restricted universe multiverse # deb-src http://archive.ubuntu.com/ubuntu xenial main restricted universe multiverse ###### Ubuntu Update Repos deb http://archive.ubuntu.com/ubuntu xenial-security main restricted universe multiverse # deb-src http://archive.ubuntu.com/ubuntu xenial-security main restricted universe multiverse deb http://archive.ubuntu.com/ubuntu xenial-updates main restricted universe multiverse # deb-src http://archive.ubuntu.com/ubuntu xenial-updates main restricted universe multiverse deb http://archive.ubuntu.com/ubuntu xenial-proposed main restricted universe multiverse # deb-src http://archive.ubuntu.com/ubuntu xenial-proposed main restricted universe multiverse deb http://archive.ubuntu.com/ubuntu xenial-backports main restricted universe multiverse # deb-src http://archive.ubuntu.com/ubuntu xenial-backports main restricted universe multiverse ###### Ubuntu Partner Repos deb http://archive.canonical.com/ xenial partner # deb-src http://archive.canonical.com/ xenial partner