Cannot download a file

 download() {
  const url = '';, this.file.dataDirectory + 'Kaalam_Yen_Kadhali-StarMusiQ.Com.mp3',true).then((entry) => {
    console.log('download complete: ' + entry.toURL());
  }, (error) => {
    alert("Server Down");

I am trying to download a file from a serve.
The file is not downloading, it shows the error.
I would like it know if their any thing that i missed.
Or any mistake in my code.
Thanking you.

What error does it show?
What is your ionic info output?