Can Someone help debug?

Hi,

I'm trying to make a call to see the available inventory there is in the system. Can someone provide their insight on what I maybe doing wrong?

SearchInventory Service

1. add site using addSite - Working
2. activate site using ActivateSite - Working
3. created order with addOrder - Working
4. group added using addAdGroup - Working
5. target profile is created with addTargetingProfile - Working
6. to add placement used addPlacement – Problem coming here

We are running following code and it returns an internal server error.

$placement_service = createClient("PlacementService", $advertiserAccountID, $accountLocation);
$placement = execute($placement_service,"addPlacement",
array("placement"=>array(
'adGroupID'=>100285389,
'startDate'=>'2010-02-01T00:00:00-05:00',
'guaranteedSettings'=>array(
'adFormatID'=>'2075001',
'pricingModel'=>'CPM',
'revenueModel'=>'NotApplicable',
'deliveryModel'=>'Impressions',//ImpressionBased
'contentTopicID'=>array('ID'=>4788501),
'placementTarget'=>array(
'ID'=>'SelfManagedPublisher',
'type'=>'SelfManagedPublisher',
),
'adSizeID'=>2082501
),
'endDate'=>'2010-02-05T00:00:00-05:00'
)
)
);


Much appreciation if someone can help out