Why can't I get inventory from CS GO via the Steam API?

Question

API

Hello!
When I try to get a list of inventory of a Counter Strike GO player via the Steam WEB API, I get an empty array.
Example:

http://api.steampowered.com/IEconItems_730/GetPlayerItems/v0001/?key=МОЙ_КЛЮЧ&steamid=76561198151869851

Although it works with other games:

http://api.steampowered.com/IEconItems_570/GetPlayerItems/v0001/?key=МОЙ_КЛЮЧ&steamid=76561198175255633

What can be wrong? Thank you!