thanks , i read that topic,
maybe this is because of suspicious IP,
but i do not know why my IP will be suspicious.
No, your problem is not related to suspicious IP.
https://bitcointalk.org/index.php?topic=423995.0New users can now immediately start posting unless they are using suspicious IPs. Suspicious IPs are ones that have been banned previously, or are known proxies, or are near many banned/proxy IPs. If you register using a suspicious IP, you can use most forum features (watchlist, etc.), but you can't post or send PMs until you pay a small fee. In almost all cases, the fee is less than $1. People proxybanned in this way can also be whitelisted by the usual people who can do whitelisting. These IP bans apply only to registration: you can no longer get caught by random IP bans if you're using an established account.