How do I trap a "file format not valid" alert from Excel?

I´m trying to open some recovered files from HD crash, see if its openable, if not close Excel and delete the file.

Excel throws a “file format not valid” alert.

This alert keeps me from being able to do multiple files ( I have hundreds)

I have to stop for each file and press “ok” on the alert to continue.

I want to trap the error and close excel and erase file if not valid.

set theFile to choose file default location "/Users/xxxxx/Documents/DataRecoverydocs/Document/xlsx/"

tell application "Microsoft Excel"
		open theFile --Excel throws an alert "file format not valid" 
                                    --it´s a recovered file maybe corrupt
	on error
		display dialog " Excel could not open the file" --this is not working to trap Excel error!
	end try
	delay 2
end tell

Thanks very much!