Reading XML in PHP... :(

Hello, I am using simplexml_load_string() function. I am having an issue extracting values. I am able to print_r($xml); and return the following:

SimpleXMLElement Object ( [0] => 31292 378 705595 Mr. Graham bgraham@arenastage.org 7002 5 Declined N 0 AF14-ON 1 Velocity Show 2014 me and my friends )

The source appears as follows:

SimpleXMLElement Object
(
    [0] => <ExecuteLocalProcedureResults>
  <LocalProcedure>
    <evex_no>31292</evex_no>
    <campaign_no>378</campaign_no>
    <customer_no>705595</customer_no>
    <lsal_desc>Mr. Graham</lsal_desc>
    <email_address>bgraham@arenastage.org</email_address>
    <source_no>7002</source_no>
    <inv_status_id>5</inv_status_id>
    <invitation_status>Declined</invitation_status>
    <reserve_ind>N</reserve_ind>
    <num_attendees>0</num_attendees>
    <notes xml:space="preserve"> </notes>
    <campaign_name>AF14-ON 1 Velocity Show</campaign_name>
    <fyear>2014</fyear>
    <source_name>me and my friends</source_name>
  </LocalProcedure>
</ExecuteLocalProcedureResults>
)

OK now to the point....

I would like to know why print_r($xml->campaign_name) will not work and how to extract the values.I am sure that I am missing something. I know enough PHP to get into trouble, but have hit a wall with this issue. Side note: I am able to extract the values using sub string, but that can't be the best, right, or most efficient way to extract the values.

example:

$xml = simplexml_load_string($response);

print_r($xml->campaign_name);

Any help/ideas would be awesome!

Thanks,

Travis