Parties that fail to post may have been scheduled incorrectly, or the group that's linked may not be set up correctly. Once the problem is fixed, you can get that party rescheduled.
Reschedule a Party:
First, delete the failed party to avoid confusion. Click Parties, then click the Delete icon (looks like a trash can) to the far right of that party.
Next click New Party at the top of that page, and follow the prompts to input the correct party details. (Note: If the party had been posting and you want it to pick up where it left off, make sure you select the same start date as the original party. That way it will skip anything already posted).
Once the new party is scheduled, you can make edits to it if you'd like. To access the party details page, click the name of that party. This will open the details page where you can easily view, edit, and adjust the posts.
Reschedule individual failed posts:
Click Parties from your dashboard menu
Click on the name of the party you want to update
Locate the failed post you want to reschedule
To the far right of that post, click the Quick Edit icon (looks like a pencil with lightning bolt)
Select the new Time (and Day, if needed)
Click Save to save your changes
That post will then be rescheduled for that new Time/Day.