[Nagiosplug-help] "Could not open ntpdate" error in check_ntp (nagios-plugins 1.4) 1.20

[Sean Staats]

I have verified that ntpdate is in the nagios user's PATH:
nagios at monitor:>which ntpdate
/usr/sbin/ntpdate

...and that ntp is working on the server:
nagios at monitor:>ntpdate -q server
server 172.29.10.25, stratum 3, offset -0.002397, delay 0.02577
 2 Mar 10:20:02 ntpdate[4821]: adjust time server 172.29.10.25 offset
-0.002397 sec

...but get the following when trying to use check_ntp:
nagios at monitor:>./check_ntp -H server -w 200 -c 500
Could not open ntpdate

Please help me troubleshoot and fix this problem.

Many thanks,
Sean