Usually means you will not be credited the miles. Often, I've seen that personally, when you have already been credited the miles and request it again. So, the second request (which sometimes appears) is not applicable to mileage earning.

But, if it's KLM/AF flights, be patient. KLM/AF can take up to a week to credit to your account. And, sometimes, the order of crediting is strange. JFK-CDG-AMS, CDG-AMS credited within 24 hours +/-, JFK-CDG credited in 6-7 days.

If you are concerned, you can always submit a manual request. Delta is pretty good at double checking and confirming mileage credit for partners.