vim: errorformat can't understand how to handle error for my parser

Question

I have a parser which output this kind of messages:

||     Error: M:\workdir\MyFile.ja: line 38: "Blablabla" has no license declaration
||     Error: M:\workdir\MyFile.ja: unknown attribute "blabla"
||     Fatal: M:\workdir\MyFile.ja: not generating output because of 2 earlier errors

I try to parse it with the following errorformat:

let &errorformat=&errorformat . ',' . 'Error: %f: line %l: %m'
let &errorformat=&errorformat . ',' . 'Error: %f: %m'
let &errorformat=&errorformat . ',' . 'Fatal: %f: line %l: %m'
let &errorformat=&errorformat . ',' . 'Fatal: %f: %m'

but it matches nothing. Can someone help me to points out what am I doing wrong ?

Thanks.

---

Edit 2017-06-21: I run my build command (which is a custom script) with :AsyncRun build (use https://github.com/skywind3000/asyncrun.vim plugin). The plugin simply run the command asynchronously and redirect its output to quickfix.

The symptom is that the quickfix window contain the messages without being recognized as error messages.

set errorformat contains the definitions I added.

Answer 1

Ok in fact I needed to match also the leading spaces with this errorformat:

let &errorformat=&errorformat . ',' . '%*[ ]Error: %f: line %l: %m'
let &errorformat=&errorformat . ',' . '%*[ ]Error: %f: %m'
let &errorformat=&errorformat . ',' . '%*[ ]Fatal: %f: line %l: %m'
let &errorformat=&errorformat . ',' . '%*[ ]Fatal: %f: %m'

It works now like a charm !

Thanks to markzen on freenode #vim who helped me to find out the solution.