Your comments

Can you please try to delete scheduled Tweets now? We may have found a workaround. Looks like your internet provider (or something in your computer) is blocking DELETE requests. Let us know.
Thanks. We have checked the log and found out that Twitter returned this error:

code:187, message:Status is a duplicate.

Did you sent the same tweet before manually? We'll show these Twitter errors on Schedule page to make it clear why it didn't went out.

The time is wrong. There was a bug. We'll fix it ASAP.

We are still investigating this. Sorry for the delay. We cannot find a way how to trigger the error on our machines.
But can you login? 
We haven't found in scenario in which this error can trigger. Are you sure this error is caused by ritetag? Can you please send us screenshot of the console?

Thanks for your cooperation
Can you please try to reload the page (ideally even cache) and try it again? Thanks. Sorry for the trouble.
Ok. Can you please also send me your Twitter handle?
Hi, we have just try it and it works for us. Can you send us more info about your browser and what exactly happens? Do you at least see a confirmation popup?