Create reminders using Sharepoint 2013

I hope there are some sharepoint developers here. I am in a struggle with creating task reminders in Sharepoint 2013.
This is the code that I have so far and does not work.



So what I do in here, I basically create a variable with the name Today on which I assign from the calendar the Today value. I add 7 days to it with the output in duedate and i set another variable for today.
I then create a loop while date is less than duedate, email the creator of the task, add 15 minutes and then pause for 15 minutes and send the email again.

What am I doing wrong? Please help. Thanks

 

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