log4c does not work in service mode - service

Question

I'm new to linux C programming
And I am trying to write a service runnig on a CentOS host, log4c works as my logging module.
Everything works just fine during developing and debbugging, but when I finally install and run it as a service, no logs were ever created.
But if I start it via shell, the logging seems perfect.
The script starting the service is simply:
daemon MyService -c 0
Starting by typing
./Myservice -c 0
and the logs show up
Please help, did I get anything wrong anywhere?
Oh, following are relative codes:
//----------------------wrapper.h------------------
#define SL_LOG_TRACE(cat, fmt, args...) { \
const log4c_location_info_t locinfo = LOG4C_LOCATION_INFO_INITIALIZER(NULL); \
log4c_category_log_locinfo(cat, &locinfo, LOG4C_PRIORITY_TRACE, fmt, ##args); }\
//----------------------main.c----------------------
void SomeFunc()
{
...
SL_LOG_TRACE(g_cat, "some logs");
...
//----------------log4c resource--------------
<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE log4c SYSTEM "">
<log4c version="1.2.1">
<config>
<bufsize>0</bufsize>
<debug level="2"/>
<nocleanup>0</nocleanup>
<reread>1</reread>
</config>
<category name="FileLogger" priority="trace" appender="myrollingfileappender"/>
<appender name="myrollingfileappender" type="rollingfile" logdir="." prefix="sl_log" layout="dated" rollingpolicy="myrollingpolicy"/>
<rollingpolicy name="myrollingpolicy" type="sizewin" maxsize="102400" maxnum="10"/>
//------------------LOG4C_RCPATH="/somedir/log"---------------------