XtraReport DocumentViewer以编程方式设置报告文档

I am using DevXpress 14. I want to use only one form name "FrmViewer" which contain DocumentVier to load any report I want. This is the code, the datasource is not null (debugged), but the message is "The document contain no page". I think I missed some method of the documentViewer to start printI am using DevXpress 14. I want to use only one