Been working absolutely fine for me.
For days yet, I cannot access proxy.org
Just display: nginx 502
I ordered a top 10 ad . $250
List4Proxy.com Add Proxy Sites Free
Works OK for me too. Maybe your country is blocked now. I believe they were/are using blocking scripts to cut out some visitors and proxies, vpn's etc. but your ad will still be seen, just not by the whole world. Maybe they should reduce the price to reflect this, it's seems expensive imho.
If I can't be a good example, I'll just have to be a terrible warning...
Check website whois and PR on TheSiteCheck.com