I can't get my location list to fill up. `:lex system("ls")` then `:llist` works (files are listed). But after `:lex system("ag something")`, `:llist` doesn't s

I can't get my location list to fill up. `:lex system("ls")` then `:llist` works (files are listed). But after `:lex system("ag something")`, `:llist` doesn't show anything.