Challenges can only be uploaded while your campaign is live. We encourage all participants to stay active during the duration of their campaign, so they do not run in to this. It is recommended to upload your challenge as soon as you have completed it rather than wait until the last minute to avoid this. Your admin will have set a campaign duration for your organization/subset and this will be visible to you in your dashboard. Unfortunately, if you do not upload your challenge(s) within that time, we can no longer accept your upload and you will not receive the credit for completing it.