JSON bilingual file

Hi,

Could someone help me out with this, please?

I have this JSON bilingual file and I can open it with Studio 2017 but I cannot save target file because I get an error message: "Value cannot be empty. Parameter name: expression"

Am I doing something wrong when parsing the JSON file? What should I include in "Target path"?

I need to insert the target into the second yellow highlighted line. Source is in the first highlighted line. 

Thanks a lot for your help in advance.

Núria