Crystal Report for .Net export button doesn't work

Hi,

I am new to CR. I am using Visual Studio .net 2003. I created a windows applcation with several reports using push method. And they work well except for the export button. When I press the export button, nothing happens and the whole program hangs. But when I run sample programs downloaded from businessobjects.com. Those export buttons work. I've done a lot of google search and the problem I encounter doesn't seem to be a common problem. I have no idea why this is happening. If any of you have any idea, please let me know. Thank you very much.

clhu