How to get the app version by Lookup API for the app available only to specific businesses

[JinGangRed]

As the Title, I had an app which is available only to specific businesses or organizations, how can we get the app version on the App store by the Lookup API for the APP?

I used the link for trying: (https://itunes.apple.com/lookup?bundleId=<my app bundle id>), but I got the below response:

{
 "resultCount":0,
 "results": []
}

Any suggestion?