1 characters of unexpected output during activation

Actually, I think there is a problem. I cannot get the PlusCaptcha image to ever acknowledge I have lined it up correctly so comments cannot be posted.

Update: I have upgraded WordPress to the latest version, WordPress 4.5.3 and PlusCaptcha is still rejecting every attempt at lining up the image correctly. I have tried over 20 times and none are accepted.

I have left it activated so the bug can be witnessed. My web site is:

blog.NoNewWars.co.uk

I have disabled it, logged in to the PlusCaptcha site, reconfigured it, re-enabled it, re-configured it again and now it works again.

On re-activating it, WordPress still gives the message “The plugin generated 1 characters of unexpected output during activation. If you notice “headers already sent” messages, problems with syndication feeds or other issues, try deactivating or removing this plugin.”

Now running PlusCaptcha Version 2.4.0 on WordPress 4.7.4 running Twenty Eleven theme.

I tried posting a comment to my blog and the Captcha was not appearing. I have applied updates and de-activated and re-activated this plugin and still get:

“The plugin generated 1 characters of unexpected output during activation. If you notice “headers already sent” messages, problems with syndication feeds or other issues, try deactivating or removing this plugin.”

Do I just give up on this plugin?