wi fi - What I have to do to connect my android smartphone (Galaxy Ace S5830) to home wifi wpa2?

I searched in the internet a lot, but there's no clear answer. I have Galaxy Ace s5830 with system Android. I tried connect to home wifi network (this network is secured by WPA2), but my smartphone can't connect. I putted wpa2 password correctly for sure.

When I push "Connect" button, for a while it's "Scanning...", and then says "Disconnect". If I disable security of my home wifi network, I can connect and it's working well.

I don't know where the problem is: on the android system or hardware of my smartphone, or maybe on the router.

I heard that there are problems with Android and WiFi connection by WPA2, but is there no solution or I can't find its.

Thanks.