Loading SHA256 certificate stops Apache from running (from SHA1 certificate)

When switching from a SHA1 to a SHA256 certificate for the same CN, Apache is having a hard time restarting and running. Here's the Virtualhost lines in /etc/httpd/conf.d/ssl.conf:

<VirtualHost *:443>
  DocumentRoot "/var/www/html"
  SSLEngine on
  SSLCertificateFile /etc/pki/tls/certs/STAR_workforce_wfs.sha1.cer
  SSLCertificateKeyFile /etc/pki/tls/private/myserver.star_workforce_wfs.sha1.key
  ServerName lii-mon01.workforce.wfs

  SetEnvIf User-Agent ".*MSIE.*" \         nokeepalive ssl-unclean-shutdown \         downgrade-1.0 force-response-1.0
  SSLCipherSuite AES256-SHA:2048:1024:256:HIGH:!ADH:!MD5:!aNULL
  SSLProtocol all -SSLv2

  ProxyRequests off
  ProxyPass /livonia/ http://localhost:5000/livonia/
  ProxyPassReverse /livonia/ http://localhost:5000/livonia/

  ErrorLog logs/nagios-error_log
  LogLevel warn
  LogFormat "%h %l %u %t \"%r\" %>s %b \"%{Referer}i\" \"%{User-Agent}i\"" combined
  CustomLog logs/nagios-access_log combined
</VirtualHost>

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Here is the nagios-error_log in /logs:

[root@lii-mon01 certs]# cat /etc/httpd/logs/nagios-error_log
[Mon May 18 08:23:57 2015] [error] Unable to configure RSA server private key
[Mon May 18 08:23:57 2015] [error] SSL Library Error: 185073780 error:0B080074:x509 certificate routines:X509_check_private_key:key values mismatch
[Mon May 18 10:43:09 2015] [error] Unable to configure RSA server private key
[Mon May 18 10:43:09 2015] [error] SSL Library Error: 185073780 error:0B080074:x509 certificate routines:X509_check_private_key:key values mismatch

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Is this because the private key and certificate don't match? I am almost sure that they were issued at the same time and pair.

Please advise.