It is considered good manners here to always mark a post as solution in a question thread, unless of course none of the posts actually provide a solution. For one thing, it helps other people who read the thread later on, to see what the solution (or the best solution) really was, and for another it gives the person who posted the solution 5 rep points.

Yeah, that makes sense, thank you. And thanks again to all that have posted!

The weirdest thing is that this feature is already there, it just only appear when you have updates. I don't know why it's not always active.. maybe it has a negative impact on the site performances or something like that or it's just a bug.