Class 'PHPExcel_Writer_Excel2007_RelsVBA' not found

Hi Guy's

Used this extension a few times without issues.

But on a new install of 1.5.6.4 with default template I'm getting " Class 'PHPExcel_Writer_Excel2007_RelsVBA' not found " error when trying to export.

I've reinstalled the extension files.

Any ideas? Can anybody help?

Thank you