Hi,
It may be because of the following issue:
# Un-check the option under File->Preferences->Excel Options->Optimize Spreadsheet.
# Check whether you are using the upgraded flash version.
#check with the variables and the filter that everythink you are passing as key not as text.
# It occurs sometime if you have more no of rows,so for a check try to publish with 255 rows if it gets published u need to optimize using your query by fetching all your data from the result rows.
Hope this will solve your issues.
Thanks & Regards
Vignesh VL