Custom function in extra showing blank page?

public function displayData($scriptProperties){
		
		$view = $scriptProperties['view'];
		
		$dataOut = '';
		
		switch ($view){
			
			// display program data
			case 'programs' :

			$programs = $this->modx->getCollectionGraph('Programs', '{ "ProgramNames":{},"Locations":{},"StatusFlags":{} }');
			
			if(!$programs) return 'not a collection';
			
			foreach ($programs as $program){

				if (is_object($program)){

					$programData = $program->toArray();  
					$programData['prog_name'] = $program->ProgramNames->get('name');
					$programData['prog_comment'] = $program->ProgramNames->get('comment');
					$programData['status_flag'] = $program->StatusFlags->get('flag');
					$programData['loc_name'] = $program->Locations->get('location');
				      
				}

				$dataOut .= $this->modx->getChunk('ProgramsViewRowTpl',$programData);
				echo '<pre>';print_r($dataOut);echo '</pre>'; // shows content of $dataOut
			}
				echo '<pre>';print_r($dataOut);echo '</pre>'; // shows nothing!! blank page
			$output = $this->modx->getChunk('ProgramsViewWrapperTpl',array('programdata'=>$dataOut,));

			return $output;
					
			break;
			
			
		}
		
	} // end getPrograms

<!-- ProgramsViewWrapperTpl -->

<table class="table">

	<thead>
	
		<tr>
		
			<th>Location</th>
			
			<th>Fund</th>
			
			<th>Start Balance</th>
			
			<th>End Balance</th>
						
			<th>Start Date</th>
			
			<th>End Date</th>

			<th>Status</th>
		
		</tr>
	
	</thead>
	
	<tbody>
	
		[[+programdata]]
	
	</tbody>

</table>

<!-- ProgramsViewRowTpl -->
<tr>

	<td>[[+loc_name]]</td>

	<td>[[+prog_name]]</td>

	<td>[[+start_balance]]</td>

	<td>[[+end_balance]]</td>

	<td>[[+start_date]]</td>

	<td>[[+end_date]]</td>

	<td>[[+status_flag]]</td>

</tr>

<!--[[+id]][[+created]][[+modified]][[+status_id]][[+location_id]][[+program_name_id]][[+start_date]][[+end_date]][[+start_balance]][[+end_balance]][[+comment]][[+prog_name]][[+prog_comment]][[+status_flag]][[+loc_name]]-->

global $modx;