API Problem

Hi All!
I would like to use API.
I did my work step by step using documentation:

Unfortunatery something is brooken:(

I want to use it within my app so I have to use proxy
That addres works fine

but when I run it via my proxy I recive default answer

using recommended proxy I receive internal error 500:

What is strange, using the same proxy on other domai, but the same server works differently:

Help! How to force it to work for me?