Why isn't searching on the command line using ag working?

Question

I'm using Mac High Sierra. I have this version of "ag", the silver searcher installed

localhost:jsminer-master davea$ ag --version
ag version 0.31.0

Features:
  +jit +lzma +zlib

I like ag because its really easy to use on the command line. However, its not working. I type this command

localhost:jsminer-master davea$ ag 'cmds:' .
localhost:jsminer-master davea$

and get nothing. Yet when I use a grep expression, something comes up

localhost:jsminer-master davea$ grep 'cmds:' ./node_modules/stratum/test/tests.js
        expect(stratum.Server.getStratumCommands(new Buffer(buffer.join('\r\n')))).to.eql({string: buffer.join('\n'), cmds: [

What's going on? How do I fix ag or is there something else I should install to quickly find text in a bunch of files?