Cant see contact "last seen online time" Does this contact not want me to see when last he was on line then? I can send him messages as well as chat.
It may mean that your contact is using a privacy option to keep that information private:

https://www.whatsapp.com/faq/en/general/20971848

"Through our privacy settings, you have the option to control who can see your last seen."

There are a few reasons why you may not be able to see a contact's last seen:


They may have set their privacy settings to hide this information.
You may have set your privacy settings to not share your last seen. 
If you do not share your last seen, you cannot see other people's last seen.
You may have been blocked.