The most common reason is the problem with your data format. See the instruction below:
Check our examples for the most common types of charts. If you have checked our examples and you make sure that your data is correct contact our support through these channels:
Slack channel: Chart plugin
Official email: [email protected]
Twitter account of our founder Pavel Kuligin: https://twitter.com/pavelkuligin93
Another common issue is the connection to our server because it is in RU zone. If you cannot fix your DNS to make it work — contact us and we will try to help you or will proceed with a refund.