Quote:
if i click yes the file does open properly but is there any way to stop this message from appearing?
Yes, there is away.
Either you make the contain really xls, either name correctly the file.
When you name a file .xls, excel expect the contain of the file to be encoded in a specific way. if it is not, excel complain with the message you get.
Quote:
i have a problem when i export a datatale to excel.
Anything depend on how your data is exported, the most common file format is some kind of text file like csv format, but without detail on the command used or a sample of the contain, it is impossible to tell further.