Erro ao gerar ficheiro em Excel

Ola
ao tentar gerar uma listagem para excel obtenho o seguinte erro:
Fatal error: Uncaught exception ‘Exception’ with message ‘Can’t create temporary file’ in /home/cmrbrava/public_html/imp/_lib/prod/third/phpexcel/PHPExcel/Shared/OLE/OLE_File.php:90 Stack trace: #0 /home/cmrbrava/public_html/imp/_lib/prod/third/phpexcel/PHPExcel/Writer/Excel5/Workbook.php(604): PHPExcel_Shared_OLE_PPS_File->init() #1 /home/cmrbrava/public_html/imp/_lib/prod/third/phpexcel/PHPExcel/Writer/Excel5/Workbook.php(572): PHPExcel_Writer_Excel5_Workbook->_storeOLEFile() #2 /home/cmrbrava/public_html/imp/_lib/prod/third/phpexcel/PHPExcel/Writer/Excel5/Workbook.php(235): PHPExcel_Writer_Excel5_Workbook->_storeWorkbook() #3 /home/cmrbrava/public_html/imp/_lib/prod/third/phpexcel/PHPExcel/Writer/Excel5.php(309): PHPExcel_Writer_Excel5_Workbook->close() #4 /home/cmrbrava/public_html/imp/grid_marcas/grid_marcas_xls.class.php(314): PHPExcel_Writer_Excel5->save(’/home/cmrbrava/…’) #5 /home/cmrbrava/public_html/imp/grid_marcas/grid_marcas_xls.class.php(27): grid_marcas_xls->grava_arquivo() #6 /home/cmrbrava/public_html/i in /home/cmrbrava/public_html/imp/_lib/prod/third/phpexcel/PHPExcel/Shared/OLE/OLE_File.php on line 90

Sujestões.
Obrigada