Java log4j appender有时不被调用

我有四个appender，有时工作，有时不调用？ 这是log4j.conf：

 # Trace appender
    log4j.appender.WsAppender=it.tracciaturaEventi.WsTraceAppender
    log4j.appender.DbAppenderOld=it.tracciaturaEventi.DbTraceAppenderOld
    log4j.appender.DBAppender=it.tracciaturaEventi.DBTraceAppender
    log4j.appender.JAppender=it.tracciaturaEventi.JAppender

    ### trace conf
    log4j.logger.it.a.b.TRACING=info, WsAppender, DbAppenderOld,DBAppender,JAppender
    log4j.additivity.it.a.b.TRACING=false
    log4j.logger.it.a.b.TRACING.c=info, WsAppender, JAppender
    log4j.additivity.it.a.b.TRACING.c=false
    log4j.logger.it.a.b.TRACING.d=info, DbAppenderOld, DBAppender
    log4j.additivity.it.a.b.TRACING.d=false

这是一个类追加器

 public class WsTraceAppender extends appenderSkeleton {
        @Override
        public void append(LoggingEvent ev) {
            TraceTO msg = msg(ev);
            if (msg == null) return;
            try {
                TraceWS.callWS(msg.properties);
            } catch (Exception e) {
                throw new TracingRuntimeException(e);
            }
        }
    }

在某一天，有时工作正常，但在另一天没有调用，而且我的日志中没有错误

对不起，我的英语不好