Problem with captcha in api vkontakte

Question

API

I try to execute a request from the application
https://api.vk.com/method/messages.get?access_token=TOKEN&count=1

, I get a captcha request, I add it to the end of the request &captcha_sid=SID&captcha_key=KEY

and I still get a captcha request.

The option that the captcha was entered incorrectly is excluded - at least once and two dozen, I would have entered it correctly anyway.

Where can you dig? What could be causing the problem?