Google Ads script integration

Hi team! 
we are using Google Ads integration 

[GET] https://api.calltrackingmetrics.com/api/v1/accounts/<account_id>/calls/ad_extensions_script

 headers: {"Authorization": "Basic " + Utilities.base64Encode(access_key + ":" + access_secret),"Content-Type": "application/json" }

The response.status_code=200   BUT  response.text = ' '  its not returning any data..

CAN YOU PLEASE HELP ?