I am trying to use Data fusion to get detail report of my Google ads MCC level. I did the following

1. Have a test developer account token on my MCC
2. Generated the refresh token
3. Generated the client ID & client secret
4. Authorised Google ads API to access my account

I added all the needed credentials in the properties section but It gives me the following error Exception while downloading report definition :null

I think the problem is with the fields as I tried to add fields such as Clicks Ad_Name & Date but still getting the same error even after changing the fields over and over again. Any idea why this is happening?