Wpomatic WP-o-Matic

I have a number of wp-o-matic blogs setup on many different domains, and I am not able to get the unix cron statement to work.

First I am very familiar with cron and use it all the time. I have crons running for many server processes. I have been doing this for years.

Second the pseudo cron (internal to wp-o-matic) works fine, that is what I have been using. However, after a while the multiple executions have started bogging down the server with cpu usage spikes.

I want to control the timing of the executions using unix cron.

The cron statement doesn't work:

*/20 * * * * /usr/bin/curl http://www.domain.xxx/wp-content/plugins/wp-o-matic/cron.php?code=x...

The webcron ready url doesn't work, either from a command line call (using curl) or in a browser. Just blank, no error messages.

The wp-o-matic log shows that a cron is being run but there are no results.

http://www.domain.xxx/wp-content/plugins/wp-o-matic/cron.php?code=x...
I have read that some tweaks to this cron statement may be needed.

Any ideas? There are several people on another forum asking this question, hope you will be able to resolve it.

Thanks
Mike