are you trying to map the n1200 at home? because in that case you should look for the local ip: very likely to be: //192.168.2.x. run the setup prog again, at least the scanning part to see what your ip is. the static ip is only for accessing from office or college.
Is it failing to login, or do you get the username / password prompt popping up and never accepting your credentials ? It could be that the credentials used for FTP and map drive are different, in which case, check that your ACL on the N1200 shard folder allow access for the user you are trying to log in with. Hope this helps.