This may be caused by several reasons.
- 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.