Errors not written to Apache error log

I've had a problem with some Apache web server error logs.

I have a virtually hosted website scotthermmann.loc on my computer. After I manually clear an error log, using

sudo cat /dev/null > scotthermmann.loc-error_log

or by opening the file in emacs & deleting all content, errors no longer get logged to the file. I've tried using

sudo apachectl restart

to solve the problem, but it doesn't solve it. Logging out & back in doesn't solve it either. What does solve it is restarting the computer, but I don't want to do that after every time I clear an error log.

This isn't the case for every website I host. I have another website barefootfool.loc. After I clear that error log, I don't have any problems.

Both virtual sites have essentially the same setup in the httpd-vhosts.conf file. For scottherrmann.loc:

<VirtualHost *:80>
    DocumentRoot "/Users/dan/Sites/scottherrmann.com"
    ServerName scottherrmann.loc
    ServerAlias www.scottherrmann.loc
    ErrorLog "/private/var/log/apache2/scottherrmann.loc-error_log"
    CustomLog "/private/var/log/apache2/scottherrmann.loc-access_log"

    <Directory "/Users/dan/Sites/scottherrmann.com">
        Options Indexes FollowSymLinks
        AllowOverride All
        Order Allow,Deny
        Allow from all 
    </Directory>
</VirtualHost>

And for barefootfool.loc:

<VirtualHost *:80>
    DocumentRoot "/Users/dan/Sites/barefootfool.com"
    ServerName barefootfool.loc
    ServerAlias www.barefootfool.loc
    ErrorLog "/private/var/log/apache2/barefootfool.loc-error_log"
    CustomLog "/private/var/log/apache2/barefootfool.loc-access_log"

    <Directory "/Users/dan/Sites/barefootfool.com">
        Options Indexes FollowSymLinks
        AllowOverride All
        Order Allow,Deny
        Allow from all 
    </Directory>
</VirtualHost>

Does anyone have an idea what could be causing the problem?