ad-blocking software that you have (for instance, the AdBlock Plus
plug-in for Firefox) - such software may cause parts of a registering
process to not appear (typically, a CAPTCHA input box, towards the
final part of the process).
There may be other complicating problems - for instance, if the forum
that you are trying to register at uses the IPB spam monitoring service,
your IP may be blacklisted - (and if I understand how that service works,
'by regarding a large number of registrations in IPB forums within a short
period of time as an indicator of a probable spammer in action', then I
suspect that possibly a large number of attempts to register may also be
regarded as an indicator of a spammer...)
(But it is really too early to make suggestions as to cause) - try the actions
in my first paragraph above - then if that doesn't work, additionally make
an attempt using an email service provider different to the one you have
previously used, (rather than merely trying to generate and use different
email addresses provided by the same email service provider each time...)
If none of the above is successful, then post here only that part of the email
address after the '@' symbol that you were unsuccessful registering with,
and also state what the date/time was in UTC
when your unsuccessful attempt occurred, so the site administrator can check
if any such attempt is actually recorded in the website logs, and if any reason
for failure is recorded.
Edited by buyerninety, 31 May 2014 - 04:49 PM.