[rtmpdump] Problem accessing the DNS

Hi guys, I'm a new comer and it will be my first question here. I'm totally new to rtmp and wanted to stream from my computer to Youtube live streaming. I can do it using ffmpeg command line tool, like: ffmpeg -i input file xx xx xx -f flv rtmp://xxxx Now I've started to write a sample c++ program using librtmp. (librtmp was compiled using "make SYS=mingw CRYPTO=" ) the URL used in the program is the URL to which ffmpeg could successfully streamed. So I think it's correct. As you can see, I had a "Problem accessing the DNS", the program was run on Windows and I've allowed it to bypass the firewall. Hope someone can help me with it. Great thanks ​