Exception :java.sql.SQLException: Duplicate entry '1-0' for key 1

Help me in fixing this error

Exception :java.sql.SQLException: Duplicate entry '1-0' for key 1

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1>>User_ID is primary key and unique and

2>>User_ID is also auto Incremented

3>>User_ID is the First coloumn in the table

PreparedStatement ps=con.prepareStatement("insert into User(user_name,user_email,user_password) values (?,?,?)");

ps.setString(1,s11);

ps.setString(2,s22);

ps.setString(3,s33);

int i= ps.executeUpdate();

[569 byte] By [saamera] at [2007-11-27 2:22:02]