Don't export multiple sheet with excel on Jasper Server 5.6.1. Please help me! It's urgent.

Hi everyone, Now, I'm using IReport 5.6.0 and Jasper Server 5.6.1 and face a issue with them. I use IReport to design a form and deploy it to Jasper Server. I want to use Jasper Server to export excel report with multiple sheet( one page per sheet). When I export excel report with IReport, I have a multiple sheet excel but with Jasper Server, I don't. I have set up in applicationContext.xml file and put line in .jrxml file. Finally, I try to export with sample report Sales By Month Report in sample folder of Jasper Server also don't export multiple sheet. What is my mistake? Please help me to explain this issue. Thank you so much.