Why doesn't this problemMatcher in VS code work?

Why doesnt my problemMatcher work? I'm pretty sure about the regex, but it doesn't report any problems, even there are some on stdout...

// the matcher
"problemMatcher": {
    "owner": "typescript",
    "fileLocation": ["relative", "${workspaceRoot}"],
    "pattern": {
        "regexp": "^TypeScript (warning|error): (.*)\\((\\d+),(\\d+)\\): (.*)$",
        "severity": 1,
        "file": 2,
        "line": 3,
        "column": 4,
        "message": 5
    }
}

//the browserify/tsify pipeline
browserify().add('main.ts')
  .plugin(tsify, { noImplicitAny: false, removeComments:true })
  .transform("babelify",{ extensions: ['.ts'], presets: ["es2015"]})
  .bundle()
  .on('error', function (error) { console.log(error.toString()); })
  .pipe(source('bundle.js'))
  .pipe(gulp.dest('www/js/dist/'));

//gulp sample output
[00:39:00] Starting 'ts-compile'...
TypeScript error: main.ts(118,30): Error TS2339: Property 'object' does not exist on type 'boolean'.
TypeScript error: main.ts(137,24): Error TS2339: Property 'object' does not exist on type 'boolean'.
TypeScript error: main.ts(507,44): Error TS2304: Cannot find name 'loading'.
[00:39:03] Finished 'ts-compile' after 2.98 s

I resolved the problem by putting tasks.json into .vscode folder. I initially thought tasks.json would be found like tsconfig.json (project-root), but it turned out to be wrong.