node.js can read only *js - files?

Example :

    var directory='C:/node/my_modules/'
    var http = require("http");
    var url = require("url");
    var fs = require("fs");
    var fn = function(request, response) {

      response.writeHead(200, {"Content-Type": "text/plain"});

      fs.readFile(directory+'first.js','utf8',function(err,data){
            if(err){
                console.log(err)
                console.log('cant openfile')
            }
        console.log(data)
      })

      response.end('_testcb("param")');
    }


    function start(){
    http.createServer(fn).listen(1337);
    console.log('start Server');
    }

exports.start = start;

This example works ....In console i see data from file .

But when fs.readFile(directory+'my.txt' then error :

ENOENT, "no such file or directory"

How to get the contents of the my.txt file

my.txt is in the same directory as first.js