I need an answer for this please! I have searched this site and find NO answers!

I play Candy Crush on Facebook from my lap top. Many friends play on mobile from other devices.  Some friends send requests that I never get The the request notification  will show up on my  Face book, but if I load Candy Crush Saga the request isn't there. No matter how much time passes. Weeks even. If I check the in game messages envelope and still nothing. These friends  send requests for lives or tickets over and over again. Why is this and how can I fix it or how can they fix it?