"What is the quality of your intent?" - Thurgood Marshall
Quote by Dani
First make sure that neither of you have selected the option to only receive PMs (private messages) from friends.
If I'm not mistaken, friend requests are sent in the form of a PM, and only receiving PMs from friends may or may not affect how/if you receive friend requests.
If this isn't your issue, then it may be a glitch, in which case you could send a message through the 'contact us' link under the Help section, and it will be sent directly to someone who can fix it for you.