Found the problem, it has to do with a plugin named theme my login,
I deactivated the plugin and it works, but existing free membership level is still not showing,
at last I need to create new membership level just to make it shows,
Here I have attached the screenshot,
Here is the account for wordpress login
Site: http://www.investormuda.com/site/
user: seventhqueen
pass: 7thqueenrocksman
Thanks,
Tommy