Google App Engine trowing error for PHPExcel

Question

I want to insert a logo in excel file. In development server it is working perfectly, but after i deployed it to Google App Engine and tried it i am getting error message from App Engine

Error: Server Error

The server encountered an error and could not complete your request. Please try again in 30 seconds.

if i remove the below part from my code it is working fine but with out logo.

$tejalogo = new PHPExcel_Worksheet_Drawing();
  $tejalogo->setName('logo')
        ->setDescription('logo')
        ->setPath('logo.gif')
        ->setHeight(36)
        ->setCoordinates($A.$n)
        ->setOffsetY(4)
        ->setOffsetX(5)
        ->setWorksheet($objPHPExcel->getActiveSheet());

i am very confused by this problem. can anyone help me?