As the title, how to upvote a solution?
I tried to click on the "upvote icon" but nothing happened, every solution I tried is the question I solved,
is there any condition I haven't reached so I cannot vote for it?

Updated: As pic, is this the button I can click to vote? Or is it else where?

2 updated: Ohhh I finally got the place to vote, it's on the left-down corner, after u click the solution you want to see, the voting button will display there, thanks for your help!