Itunes search API won't show existing app info

Not all apps are available in all countries. For the poker app it's in the US store so your first URL finds it, but the second URL is looking for it in the Russian store (you have '/ru' in the address) and the app isn't in the Russian store so it doesn't find it (either the developer hasn't granted Apple a license to sell it there or Russian laws aren't allowing it). Changing that URL to be for the US store does find it : https://itunes.apple.com/us/lookup?id=606944207