Are you on one called "Trouble in Skyrim"?
No, it's not in my quest log.
I haven't done the companions quest line yet but according to the guide there is prerequisties to finish the companions' proving honor quest and one faction radiant quest before you can do the silver hand quest.
The radiant quest givers are; Aela gives an animal incursion quest and Farkas gives an hired musle quest.
Hope this helps.
"Proving Honor" is done, it's in my completed section of the quest log. From Aela or Farkas I don't remember taking quests, but even if I did, why wouldn't they appear in the journal? And why do they tell me to do the quest given by Skjor before they have work for me... as long as I don't have any quest by Skjor in the log

I think the only reasonable explanation would be Skjor already gave me the Silver Hand quest but for some reason it doesn't start, it's not in my journal and Skjor is not going to the meeting point at night. I wish I could "undo" the last completed quest and do it again.