export sometimes does not work in preview

I am using the preview function. I am using the frxReport-opbject and the export-objects like frxPDFExport. I am making a normal preview, and everything is shown perfect. I am using 3 different possible reports (fr3-files). In all three i get the message, that let me select the configuration like "compressional, embedded font,.." in PDF Export or the same in the other exports. But the strange point is, that in one of the 3 report i get absolut no reaction after pression the OK-Button, in the 2 others I get the question where to save and it also works perfect. I checked all and don't find any difference between the 3 different versions. In the export and in the rreport i set the ShowDialog to True. So what else can be the reason. I have absolut no idea anymore what can be the reason for this behavior.

Thanks for every ansswer

chaosworld

PS: The strange thing is, that in report 1 it never works, in report 2 and 3 it always works. And more stange is, I also use the Designer, if i opne the designer after the printing, i can open report 1, 2 and 3. If I printed report 1 before, the export does not work in the preview-function of the designer, but if I printed before report 2 or 3, the export works with all 3 reports.