Mail Merge Failure when Merge more than 20 Records


I'm hoping someone can help me.
I noticed that when I try to mail merge more than 20 records to a word certificate doc, the system provides the following error:

Mailmerge generation failed
Exception in thread "main" com.sage.crm.core.exception.MailMergeException: com.sage.crm.core.exception.MailMergeException: java.lang.NullPointerException: srcDoc

This above error comes directly from the SQL log file (which I set to 5 to see what was happening).

Is there a way to increase this threshold to 500?

Let me know.