Live Office argument cannot be null

Hi

I need to create a live office report. The webi report imported to EXCEL has a date prompt. I can refresh the report in Lauch Pad without any date prompt problem, but when  I imported the same report to EXCEL, and tried to refresh the live office report. It showed "Failed to get the document information.(Lo 26315). Argument cannot be null.(Error:RWI 00010) error", even though I gave the prompt argument which is a date selected from Calender.

Can any one please help on this issue

Thanks

Dave