error with a Query mercury

[GheddoMonsta]

Hello i Have a error with a query in Mercury

queryreactor2.runFastQuery("INSERT INTO verwarnungen (username, grund, massnahme) " + "VALUES (" + this.GetHabbo().Username + ",unnoetig, wtf);");

the errorlog Say:

INSERT INTO verwarnungen (username, grund, massnahme) VALUES (Crysas,werben, lol);
MySql.Data.MySqlClient.MySqlException (0x80004005): Unknown column 'Crysas' in 'field list'

Crysas is my Username?

[MentaL]