Hi,
Please do hard clean of cache. Go to below specified path:
C:\Users\<your username>\AppData\Roaming\Neolane\NL_5
and delete all xml files except 'nlclient_cnx'
Then try to login again.
Also, please verify whether credential you are using is valid or not using below URL:
http://<serverurl>/nl/jsp/logon.jsp
If you are not able to do web login, then your credentials are incorrect.
Thanks.