You may have already asked these friends for help earlier today. The daily reset time is 2am UTC (that's 6pm PST or 9pm EST). You can only ask for help 1 time in 24 hours and you can only help your neighbors 1 time in 24 hours.
Make sure that you're actually Facebook friends with people you don't see in your list. Visit their page and see if they're friends with you.
Your app may not have been given proper friend list permissions. Please follow these instructions to adjust your app settings.