some ISP are unable to hear my stream

[Squalo]

some guys can't hear my stream, all my config is ok it is running perfectly

but the problem is the ISP they have

how can i correct this problem
my log file is this

Event log:
<02/23/04@18:12:20> [SHOUTcast] DNAS/win32 v1.9.2 (Nov 25 2002) starting up...
<02/23/04@18:12:20> [main] loaded config from C:\Archivos de programa\SHOUTcast\sc_serv.ini
<02/23/04@18:12:20> [main] initializing (usermax:32 portbase:8000)...
<02/23/04@18:12:20> [main] No ban file found (sc_serv.ban)
<02/23/04@18:12:20> [main] No rip file found (sc_serv.rip)
<02/23/04@18:12:20> [main] opening source socket
<02/23/04@18:12:20> [main] source thread starting
<02/23/04@18:12:20> [main] opening client socket
<02/23/04@18:12:20> [main] Client Stream thread [0] starting
<02/23/04@18:12:20> [main] client main thread starting
<02/23/04@18:12:20> [source] listening for connection on port 8001
<02/23/04@18:12:27> [source] connected from 10.21.84.59
<02/23/04@18:12:28> [source] icy-name:ConeXion 101 - te enchufas o te conectas ; icy-genre:Rock
<02/23/04@18:12:28> [source] icy-pub:1 ; icy-br:128 ; icy-url:www.conexion101.2ya.com
<02/23/04@18:12:28> [source] icy-irc: ; icy-icq: ; icy-aim:
<02/23/04@18:12:29> [dest: 205.188.234.73] starting stream (UID: 0)[L: 1]{A: SHOUTcast Directory Tester}(P: 0)
<02/23/04@18:12:29> [dest: 205.188.234.73] connection closed (0 seconds) (UID: 0)[L: 0]{Bytes: 8192}(P: 0)
<02/23/04@18:12:30> [yp_add] yp.shoutcast.com added me successfully

but it doesn't even detect their IP