why supreport overlapped by page header in ireport

[raindrop2010]

 I design a report in iReport with windows + weblogic, and there is a page header and detail column, and I place a subreport in the detail column. It works well in windows + weblogic! But when I deploy it to linux + weblogic, I found that whenever there is a new page in Detail column, the subreport content in detail column will be overlapped by page header. It seems that when it create a new page, it can not realize the position of page header.

I have set the subreport's "Position type" to float, but don't work while everything is OK in windows + weblogic.

Thanks in advance !