Easyblog cron "wget" only works on second attempt

I have an easyblog cron job that fails when run automatically.

When it is run manually from a command line it fails with a "500- Server error" the first time it is run, but succeeds the second time.

The Apache log looks like this

139.162.200.22 - - [04/Apr/2016:13:54:02 +0000] "GET /index.php?option=com_easyblog&task=cron HTTP/1.1" 500 276 "-" "Wget/1.16 (linux-gnu)"
139.162.200.22 - - [04/Apr/2016:13:55:01 +0000] "GET /index.php?option=com_easyblog&task=cron HTTP/1.1" 500 276 "-" "Wget/1.16 (linux-gnu)"
139.162.200.22 - - [04/Apr/2016:13:55:01 +0000] "GET /index.php?option=com_easyblog&task=cron HTTP/1.1" 200 979 "-" "Wget/1.16 (linux-gnu)"
139.162.200.22 - - [04/Apr/2016:13:55:01 +0000] "GET /index.php?option=com_easyblog&task=cron HTTP/1.1" 200 979 "-" "Wget/1.16 (linux-gnu)"
139.162.200.22 - - [04/Apr/2016:13:55:51 +0000] "GET /index.php?option=com_easyblog&task=cron HTTP/1.1" 500 276 "-" "Wget/1.16 (linux-gnu)"
139.162.200.22 - - [04/Apr/2016:13:56:40 +0000] "GET /index.php?option=com_easyblog&task=cron HTTP/1.1" 200 979 "-" "Wget/1.16 (linux-gnu)"
139.162.200.22 - - [04/Apr/2016:13:57:35 +0000] "GET /index.php?option=com_easyblog&task=cron HTTP/1.1" 500 276 "-" "Wget/1.16 (linux-gnu)"


A time or timer seems to be associated in some way. It is successful on the second attempt providing this occurs less than a minute after the last failed attempt?