If you mean "not all (people) conquer love," you could say:
Non omnes amorem vincunt.
non = not
omnes = all (people)
amorem = love (object of the verb)
vincunt = conquer (they conquer, plural)
But if you want to say "not all (things) conquer love," it would be:
Non omnia amorem vincunt.
(omnia = all things; omnes = all people)
And the original saying, "love conquers all" is amor vincit omnia (not vincat; "amor vincat omnia" would mean, "let love conquer all")
I hope that helps.