[qnx6.4.0:ntpd] ntpd server is setted, why ntp.drift failed?

The /etc/ntp/ntp.conf is configured as this:
/******************************************************/

Example for the Internet server

server 192.168.1.1 #GPS NTP Server stratum 1

Example for a stand alone server

server 127.127.1.0
fudge 127.127.1.0 stratum 10

restrict 127.0.0.1 nomodify

driftfile /etc/ntp/ntp.drift
logfile /etc/ntp/ntp.log
/******************************************************/

And then start ntp server: ntpd -dg
The /etc/ntp/ntp.log logged as this:
//
24 Apr 08:30:45 ntpd[1085456]: synchronized to 192.168.1.1, stratum 1
.TEMP:Invalid argument85456]: can’t open /etc/ntp/ntp.drift
.TEMP:Invalid argument85456]: can’t open /etc/ntp/ntp.drift
.TEMP:Invalid argument85456]: can’t open /etc/ntp/ntp.drift
.TEMP:Invalid argument85456]: can’t open /etc/ntp/ntp.drift
/
/

the file /etc/ntp/ntp.log can be logged successfully, but the /etc/ntp/ntp.drift has some problem.
Can someone tell me what’s problem? and why the logfile has the infomation ‘.TEMP’? Is there any diference about the way to write ntp.drift and ntp.log. Thanks in advance.