Log4php respecting root but not logger

Question

I'm attempting to log to two different log files, one "alert.log" to be monitored, and one "debug.log" for troubleshooting. In the configuration below, the "alert.log" grows with error messages, and the "debug.log" is created as a zero-length file that never grows.

I've tried swapping the contents between "root" and "logger", and the logged messages are written as expected. It seems whatever is in "root" gets written and whatever is in logger doesn't. What might I be doing wrong?

<?xml version="1.0" encoding="UTF-8"?>
<configuration xmlns="http://logging.apache.org/log4php/">

<appender name="AlertableFileAppender" class="LoggerAppenderRollingFile">
    <param name="file" value="/var/log/example/alert.log"/>
    <param name="append" value="true"/>
    <param name="maxBackupIndex" value="0"/>
    <param name="maxFileSize" value="10000KB"/>
    <layout class="LoggerLayoutPattern">
        <param name="conversionPattern" value="%d{ISO8601} %p src=&quot;%M:%L&quot; %m%n"/>
    </layout>
</appender>
<appender name="DebugFileAppender" class="LoggerAppenderRollingFile">
    <param name="file" value="/var/log/example/debug.log"/>
    <param name="append" value="true"/>
    <param name="maxBackupIndex" value="0"/>
    <param name="maxFileSize" value="10000KB"/>
    <layout class="LoggerLayoutPattern">
        <param name="conversionPattern" value="%d{ISO8601} %p src=&quot;%M:%L&quot; %m%n"/>
    </layout>
</appender>
<appender name="ConsoleAppender" class="LoggerAppenderConsole">
    <layout class="LoggerLayoutPattern">
        <param name="conversionPattern" value="%d{ISO8601} %p src=&quot;%M:%L&quot; %m%n"/>
    </layout>
</appender>

<logger name="SecondLogger">
    <level value="DEBUG"/>
    <appender_ref ref="DebugFileAppender"/>
    <appender_ref ref="ConsoleAppender"/>
</logger>

<root>
    <level value="WARN"/>
    <appender_ref ref="AlertableFileAppender"/>
</root>


</configuration>

Answer 1

Rewriting the config to use threshold="warn" on the AlertableFileAppender and putting both appender references in root worked for me. I removed logger and set the root level to "all".