Problem while generating the report

I set up the ELA to send mails when reports are generated, in testing this worked once, but now it does not generate any reports.

The report is made out of all windows hosts, and has a filter that will only display errors/failures/warnings from the past 24 hours.

now i get the following message:

Dear Administrator,

This mail is the result of EventLog Analyzer Reports Generation Engine.
Problem while generating the report.[Failures/Warnings/Errors_Apr_13_2007_11_46_15.pdf]

Report details:

Report Name: Failures/Warnings/Errors
Report for Machines: "Servernames"
Generated Time: Fri, Apr 13, 2007, 11:46:15
From: 2007-04-12 11:46:15
To: 2007-04-13 11:46:15

Reports Included :-

Security based events
Directory Service based events
Application based events
File Replication based events
System based events
DNS based events
Summary of SysLog events
SysLog events