Laptop can scan but cannot connect to wifi!!HELP!!?

[duopoon]

So here is the deal,
I got a Lenovo X131e laptop and a Tenda n450 router, newly bought.

I put my router at my sitting room and my laptop at my bedroom
They are separated by a wall (either concrete w/ reinforcement or brick)

When I have my laptop at my sitting room, I can scan and connect to the internet with no problem. Once I move my laptop to my room, it can scan(80%) and find my router but can't connect to it.

If you think the wall block the signal, I guess it's not the case, coz my cellphone can connect to the wifi anywhere at my house.

Is there any setup step I have missed causing the abovesaid? any solution will worth a try

[Steven]

maybe your wifi modem in computer is dirty of powder.. use compressed spray to clean your laptop