Facebook android help?

[Thirsty Kirstie! xD]

I just got my android phone and it won't let me log into my facebook! I tried resetting my password on my computer and uninstalling the app and updating it and it still didn't work at all. It logged into my mom's account no problem but won't log into mine. Any help?????
It logged into my browser just fine and it says I already have the app installed. It just won't let me log into my app but it'll let my mom when it's her account....