I ran into a similar problem with a couple of scripts. This is from the documentation of PhpAds. It seems that if you want to run a php script with cron, you have to use commands similar to these.
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Depending on the configuration of
your server you can use one of the following tools to actually run the maintenance file:
curl, fetch, lynx or wget. To find out which is supported by your server simply type the
name of the tool on the command-line. If you get a message ?command not found? the tool
isn?t supported on your server.
# if your server supports curl:
0 * * * * curl -s -o /dev/null
http://your.server.name.here/phpAdsN...aintenance.php
# if your server supports fetch:
0 * * * * fetch -o /dev/null
http://your.server.name.here/phpAdsN...aintenance.php
# if your server supports lynx:
0 * * * * lynx > /dev/null -dump
http://your.server.name.here/phpAdsN...aintenance.php
# if your server supports wget:
0 * * * * wget -q -O /dev/null
http://your.server.name.here/phpAdsN...aintenance.php
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On my box, it was the wget command that did the trick.
Hope this helps.....