wait condition in workflow.

Hello All,

How to write a wait condition where my scenario is as below.

1. write a workflow on task entity when record is created.

2. check the condition if the contact has email.

3. Wait till due date   equal  reminder  due date

4. send an email .
5.stop workflow.

i have used the wait condition such that Due date On {Reminder Due Date}

but it's not working expected , i mean it's not sending email.

what's wrong am i doing wrong in this any step by step suggestion.