No PDF Export

Hi Confluence Team,

when a user try's to export a space as a PDF - it get stuck at 50% when the frist site should be exported and then i found these 2 erros in
storage/atlassian/confluence/logs/altassian-confluence.log

2015-02-06 09:09:49,884 WARN [Long running task: PDF Space Export] [confluence.extra.flyingpdf.ConfluenceExportUserAgent] getImageResource Could not retrieve image resource /download/attachments/14942875/BTT_Logo_Empowering_black_web.jpg?api=v2 during Confluence export
– url: /spaces/flyingpdf/doflyingpdf.action | userName: peter.breitenecker | referer: https://confluence.braintribe.com/spaces/flyingpdf/flyingpdf.action?key=TD | action: doflyingpdf

2015-02-06 09:13:24,663 ERROR [Long running task: PDF Space Export] [com.atlassian.hibernate.HibernateObjectDao] findSingleObject Uh oh - found more than one object when single object requested: [Attachment: ProcessModel.overview.png v.1 (18612900) gregor.prokesch, Attachment: ProcessModel.overview.png v.1 (18612901) gregor.prokesch]
– url: /spaces/flyingpdf/doflyingpdf.action | userName: peter.breitenecker | referer: https://confluence.braintribe.com/spaces/flyingpdf/flyingpdf.action?key=TD | action: doflyingpdf