Using Validation Rule on form

Summary

I'm trying to use the validation rule on form to avoid submission of a task

Content

Hi All,

I would like to avoid a task submission using a validation tule on a form, so if a check account on form become "red" will be impossible, for the user, to submit the task. My idea doesn't work on system. Despite setting the validation rule that turns red on form, the user is able to submit the task, maybe I am wrong ?

The question is: is it possible to avoid the submission of a task using a validation rule on form? and how can I setup it?