OneSignal coding push problem

In an ionic project, I tried to send push when press a button, the code is like below:

message: any = {
contents: {"en": "This is content"},
headings:{"en":"This is title"},
included_segments: ["All"]

and the function is like below:

sendNotification(message) {
const body = JSON.stringify(message);
const headers:any = new Headers();
headers.append('Authorization', 'Basic XXXXXXXddkdkctM2FmNS00N2EwLWIwZmEtYTg1NjgyNTliYTUx');
headers.append('Content-Type', 'application/json');
return, body, {
headers: headers
}).map((data: Response) => data.json());

Show no error so far, but when I click the button, nothing happen.
I am sure that the app id and the api key are correct. But it just won’t work, could someone please help me to check what’s wrong with the code? Thank you.