Spreadsheet Question

Dear List, so I have a problem generating Excel files. On my local system everything is running fine, but once I upload the scripts to the hosting server, the Excel-sheet will still be generated, but it is empty and 0 bytes big when I download it. I tried to make sure that I use the same settings on my local Apache (SafeMode on and stuff). I also tried to upload the basic scripts from the tutorials I found on the internet, but still face the same problem. The headers will be send, the data won't. Might that be some php.ini settings? Thanks a lot! Stefan.