What results do you get with the code you've posted ?
What results do you get if you use Criteria1:=STARTDATE
What is STARTDATE, a variable, named range or something else ?
Where are you entering 6/15/2018 ?
What's in Field 12, "true dates", text that looks like dates, dates and times ?
What's the rest of the code ?

Providing a sample sheet indicative of what you're working with would be beneficial to getting the required solution.