How to import contacts from VK to FB?

Question

Facebook

Hello.
I have a VK account and a FB account.
VK has a two-stage entrance.
In VK, my FB application is lit, in FB, the VK application is lit.
When I click on FB in the upper right corner to find friends and then in "Add personal contacts" I press the VK button, then the Find friends button, the system writes:
"We did not find any contacts. Try another account."
What's the matter?
How to import contacts from VK to FB?