Unable to create giveaway for specific games

Hi. I´m new to the site and I wanted to create a few giveaways with some keys for games I already own, however games are not included in the list/results when I type their names. I got the games for free in other sites but they are not free games. They are not great games, but still. Does anyone know why this is?
Here are the games I wanted to give away:

Space Beret http://store.steampowered.com/app/547960/Space_Beret/ $ 0,99
Journey to the center of the earth http://store.steampowered.com/app/382120/Journey_To_The_Center_Of_The_Earth/ $ 3,99
Loot Hero DX + Soundtrack DLC http://store.steampowered.com/app/294040/Loot_Hero_DX/ $ 3,99
Vitatio 2 http://store.steampowered.com/app/586380/VITATIO_2/ $ 0,99
Action Alien http://store.steampowered.com/app/382080/Action_Alien/ $ 3,99 (currently discounted to $ 1,99)
Tap Heroes http://store.steampowered.com/app/371570/Tap_Heroes/ $ 2,99