DMARC says SPF fail even with SPF record

I have the following SPF record under the pixelark.com domain:

v=spf1 ip4:70.164.0.71  include:amazonses.com include:_spf.google.com ~all

The ip4 address is the webserver, the amazonses.com is used for Amazon SES. It is the amazon SES that is giving me the issue.

This is one of many example DMARC results I get when sending email through amazon SES.

<record>
 <row>
  <source_ip>204.197.248.33</source_ip>
  <count>1</count>
  <policy_evaluated>
    <disposition>none</disposition>
    <dkim>pass</dkim>
    <spf>fail</spf>
  </policy_evaluated>
 </row>
 <identifiers>
  <header_from>pixelark.com</header_from>
 </identifiers>
 <auth_results>
  <dkim>
    <domain>pixelark.com</domain>
    <result>pass</result>
  </dkim>
  <spf>
    <domain>amazonses.com</domain>
    <result>fail</result>
  </spf>
 </auth_results>
</record>

I am sending an email from noreply@pixelark.com through Amazon SES. I have amazonses.com as a valid sender in the SPF record but the DMARC is showing an SPF fail.

I cannot figure out why this is happening? I have not been able to figure this one out. Any help would be greatly appreciated.