CF6 - Form in Joomla Article failed the security image Check

Hi
I have a Joomla Installation (3.9.2) and chronoform 6 (installed: Chronoforms_V6.0.21_Extension.zip).
All working fine. When i made a Joomla-Menu-Point - directly on a Form, the Form will work fine. When i use this same Form in a Article with {chronoforms6}...{/chronoforms6} plugin-function, the formular will presented ok. but, when i sent the form, the security image give a message, that the false image is marked.
conclusion: my forms will not work in a Joomla-article.
whant can i do?

Use recaptcha instead
Make sure that you don't have multiple forms showing up on the one page

Hello
Thank you - but i have found the problem. The plugin was not installed. why always???
Now it work's.