Help! Spam posts by robots

[netbrain]

There have been many spam posts recently in our forum. The registered time, posted time and visited time are almost the same.
Our current vbulletin version is 3.8.2
Now we have a verification mechanism called ' reCAPTCHA', but it doesn't work to these bad posts.
Could anybody provide a good way to prevent these spam posts posted by robots?
Thanks very much!

[wda2015]

add a few more questions on register..that way seems to stop them.

[Steve Machol]

To get vB support on these forums you first need to be a licensed customer and register for Priority Forum Support. To do this, please go here:

http://members.vbulletin.com/membersupport_priority.php

...and enter your email address in one of the boxes. You'll need to have your customer number and password to access the page.

Once you've done this, please post in the appropriate support forum for your version.